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The history of Christianity begins with the ministry of Jesus, a Jewish teacher and healer who was crucified and died c. AD 30–33 in Jerusalem in the Roman province of Judea. Afterwards, his followers, a set of apocalyptic Jews, proclaimed him risen from the dead. Christianity began as a Jewish sect and remained so for centuries in some locations, diverging gradually from Judaism over doctrinal, social and historical differences. In spite of the persecution of Christians in the Roman Empire, the faith spread as a grassroots movement that became established by the third-century both in and outside the empire. New Testament texts were written and church government was loosely organized in its first centuries, though the biblical canon did not become official until 382.

Constantine the Great was the first Roman Emperor to declare himself a Christian. In 313, he issued the Edict of Milan expressing tolerance for all religions. He did not make Christianity the state religion, but he did provide crucial support. Constantine called the first of seven ecumenical councils. In the fourth-century, Eastern and Western Christianity had already begun to diverge. Between 600 and 750, the constant need to defend itself in war turned the Eastern Roman Empire into the independent polity of Byzantium. Missionary activities spread Christianity across western Europe. Monks and nuns were prominent in establishing a Christendom that influenced every aspect of medieval life.

From the ninth-century into the twelfth, politicization and Christianization went hand-in-hand in developing East-Central Europe. Byzantine Christianity influenced the church, culture, language, literacy, and literature of Slavic countries and Russia. The Byzantine Empire was more prosperous than the Western Roman Empire, but centuries of Islamic aggression and the Crusades negatively impacted it. During the High Middle Ages, Eastern and Western Christianity had grown far enough apart that differences led to the East–West Schism of 1054. Temporary reunion was not achieved until the year before the fall of Constantinople in 1453. The fall of the Byzantine Empire ended the institutional Christian Church in the East as established under Constantine, though it survived in an altered form.

Various catastrophic circumstances, combined with a growing criticism of the Catholic Church in the 1300–1500s, led to the Protestant Reformation and its related reform movements. Reform, and the Catholic Counter-Reformation, were followed by the European wars of religion, the development of modern political concepts of tolerance, and the Age of Enlightenment. Christianity also influenced the New World.

After WWII Christianity faced many challenges. Traditional Christianity has declined in the West, while new forms have developed and expanded worldwide. Today, there are more than two billion Christians worldwide.^[1][2] Within the last century, the centre of growth has shifted from West to East and from the North to the Global South making Christianity a truly global religion in the twenty-first century.^[3][4][5][6]

Early Christianity begins with the ministry of Jesus (c. 27–30)^[7] Virtually all scholars of antiquity accept that Jesus was a historical figure.^[8][9] His crucifixion is well attested.^[10] He was a complex figure, which many see as a sage, a holy man, a prophet, a seer, or a visionary.^[11] Jesus saw his identity, mission, and that of his followers, in light of the coming kingdom of God and the prophetic tradition of Israel.^[12] His followers believed he was the Son of God, the Christ, a title in Greek for the Hebrew term mashiach (Messiah) meaning “the anointed one", who had been raised from the dead and exalted by God.^[13][14] As Frances Young has written, "The incarnation is what turns Jesus into the foundation of Christianity".^[15] The Christian church established these as its founding doctrines, with baptism and the celebration of the Eucharist meal (Jesus' Last Supper) as its two primary rituals.^[16]

Christianity initially emerged in the Roman province of Judea during the first-century.^[13] It was both impacted by and impacted the geographical, cultural and socio-economic context in which it first developed.^[17] In the Roman Empire around the ancient Mediterranean, elites (2 - 5 % of the population) controlled the means of economic production, had a virtual monopoly on literacy, and most of the political power.^[18] Life for peasants was not easy, and hunger was common.^[19] 'Religion' in this context did not exist separately from politics or the family household.^[20]

The 'house church' was the earliest stage of development and organization in the new Jesus movement. The owner of the house was patron and host. Voluntary associations known as collegia served as a model. The typical setting for worship was the communal meal which was not yet formally distinguished from the eucharistic meal. Some church members were of higher social and economic standing than others and used their means to provide what was needed. These house churches would each have been overseen by a presbyter/bishop whose primary role was economic. Any liturgical role would still have been linked to the substantial character of the eucharistic meal, the resources needed for it, and the charitable distributions connected to it. Accordingly, Christian bishops began forming an alternative elite.^{[21][22][18][23]}

The first Christian communities were predominantly Jewish, although some also attracted God-fearers: Gentiles who visited Jewish synagogues.^[24][25] The religious, social, and political climate in Judea was extremely diverse and characterized by turmoil. Judaism itself included numerous religious and political movements.^[13][26][27] One was Jewish messianism with its roots in Jewish apocalyptic literature.^[28] Its prophecy and poetry promised a future anointed leader (messiah or king) from the Davidic line to resurrect the Israelite Kingdom of God and replace the foreign rulers.^[13] The nature of the earliest communities and the texts they produced indicate Jesus' first followers saw him as that promised Messiah.^[29][30]

According to Gerd Theissen, institutionalization began very early when itinerant preaching transformed into resident leadership in the first-century.^[31] Edwin Judge also argues for organization long before 325.^[32] Clement, a first-century bishop of Rome, refers to the leaders of the Corinthian church in his epistle to Corinthians as bishops and presbyters interchangeably. The New Testament writers also use the terms overseer and elders interchangeably and as synonyms.^[33] It is unlikely that Christian offices were derived from the synagogue.^[22][21]

Saul of Tarsus, a pharisee who later became Paul the Apostle, persecuted the early Jewish Christians prior to his own conversion.^[24] Paul was influential in the early spread of Christianity making at least three missionary journeys and writing letters of instruction and admonishment to the churches he founded.^[24][34][35]

Beginning with less than 1000 people, Christianity had grown to around one hundred small household churches consisting of an average of seventy members each, by the year 100.^[36]

The earliest date for the council is 47, but most likely it was held in 49 or 50. The Jerusalem church gathered to address the issue concerning Gentiles who were joining the movement in increasing numbers and the Judaizers who wanted them to follow Jewish law. Shailer Mathews explains that "The faith that was Jewish in form, and universal in content, had to be adjusted to non-Jewish people".^[37]

In its first three centuries, some saw Christianity as a threat which led to localized persecution by mobs and governors.^[38][39] The first reference to persecution by a Roman Emperor is under Nero, probably in 64 AD, in the city of Rome. Scholars conjecture that the Apostles Peter and Paul were killed then.^[40]

The Hellenized Greek-speaking Jews of Alexandria had produced the Septuagint, a Greek translation of the Hebrew Bible, between the third and first centuries BC.^[41] This was the translation of the Hebrew Bible used by the apostles and early Christians.^[42]

Christian writings in Koine Greek, including Gospels containing accounts of Jesus's ministry, letters of Paul, and letters attributed to other early Christian leaders, were written in the first-century and had considerable authority even in the formative period.^[43][44] The letters of the Apostle Paul sent to the early Christian communities were circulating in collected form by the end of the first-century.^[45]

The Second and Third centuries included both the fluidity and the consolidation of Christian identity.^[46] A more formal Church structure grew, and according to Carrington, that hierarchy developed at different times in different locations. Bishops began presiding over larger areas with multiple churches and rose in power and influence.^[33][21][47] The Ante-Nicene period included increasing but sporadic persecution from Roman authorities, and the rise of Christian sects, cults, and movements.^[48]

The destruction of Jerusalem and the Second Temple by Roman Emperor Titus in 70 contributed to the divergence of Judaism and Christianity as did disagreements about Jewish law, Jewish insurrections against Rome which Christians did not support, and the development of Rabbinic Judaism.^[49][50] What had begun as a Jewish messianic movement became a largely Gentile movement that was increasingly divorced from Judaism and its practices.^[51] However, Jewish Christianity remained influential in Palestine, Syria, and Asia Minor into the second and third centuries.^[52][53]

By the early third-century, there existed a set of early Christian writings similar to the current New Testament.^[54] Although a general acceptance of the four gospels and the letters of Paul as authoritative is found in the second and third centuries, it is significant that church leaders assigned different degrees of authority to different writings.^[55] There were disputes over the Epistle to the Hebrews, the Epistle of James, the First and Second Epistle of Peter, the First Epistle of John, and the Book of Revelation.^[56][57] Gnostic texts emerged in the early second century challenging the physical nature of Jesus. In 172, Montanism suggested that current prophecy could supersede the apostles, and Monarchianism emphasized the unity of God over the Trinity.^[58] In the face of such diversity, the scriptures commonly used in worship provided some unity.^{[59][60][note 1]}

The early church fathers rejected the making of images.^[61] This rejection, along with the necessity to hide Christian practice from persecution, left behind few early records.^[62] What is most likely the oldest Christian art emerged on sarcophagi, and in burial chambers in frescoes and statues, from the late second to the early third-century.^[63][64] This art is symbolic rather than representative. Much of it is a fusion of Graeco-Roman style and Christian symbolism.^[65][66] Jesus as the good shepherd is the most common image of this period.^[67]

In 250, the emperor Decius made it a capital offense to refuse to make sacrifices to Roman gods, resulting in widespread persecution of Christians.^[68][69] Valerian pursued similar policies later that decade. The last and most severe official persecution, the Diocletianic Persecution, took place in 303–311.^[70] There was also periodic persecution of Christians by Persian Sassanian authorities, and popular opposition from Graeco-Roman society at large. Christian authors of the second and third centuries were on the defensive, and the term Hellene became equated with pagan during this period.^[71][72]

The Edict of Serdica was issued in 311 by the Roman Emperor Galerius, officially ending the persecution of Christians in the East. With the promulgation of the Edict of Milan in 313, in which co-emperors Constantine and Licinius legalized all religions, persecution of Christians by the Roman state ceased.^[73]

The Kingdom of Armenia became the first country in the world to establish Christianity as its state religion when, in an event traditionally dated to 301, Gregory the Illuminator led Tiridates III, the King of Armenia, to convert to Christianity.

Driven by a universalist logic, Christianity has been, from its beginnings, a missionary faith with global aspirations.^[75][76] It first spread through the Jewish diaspora^[77][78] along the trade and travel routes followed by merchants, soldiers, and migrating tribes.^[79][80][81] It achieved critical mass in the years between 150 and 250 when it moved from fewer than 50,000 adherents to over a million. This provided enough adopters for its growth rate to be self-sustaining.^[80][81]

In the first-century, it spread into Asia Minor (Athens, Corinth, Ephesus, and Pergamum).^[82] Egyptian Christianity probably began in the first-century in Alexandria.^[83] As it spread, Coptic Christianity, which survives into the modern era, developed.^[84][85] Christianity in Antioch is mentioned in Paul's epistles.^[86]

Early Christianity was in Gaul, North Africa, and the city of Rome.^[87][88][89] It spread (in its Arian form) in the Germanic world during the latter part of the third-century, and probably reached Roman Britain by the third-century at the latest.^[90][90]

From the earliest days, there was a Christian presence in Edessa (modern Turkey). It developed in Adiabene in the Parthian Empire in Persia (modern Iran). It developed in Georgia by the Black Sea, in Ethiopia, India, Nubia, South Arabia, Soqotra, Central Asia and China.

By the sixth-century, there is evidence of Christian communities in Sri Lanka and Tibet.^[79][91]

Early Christianity was inclusively open to everyone (Galatians 3:28).^[92] Baptism was free, and there were no fees, which made Christianity a substantially cheaper form of worship compared with the costly aristocratic models of patronage, temple building, and cult observances.^[93][94] Inclusivity extended to women who made up significant numbers of Christianity's earliest members.^[95] Traditional social expectations of women in the Roman Empire did not encourage them to engage in the same activities as men of the same social class.^[96] However, through religious activities, women were sometimes able to attain a freedom otherwise denied to them.^[97]

The Pauline epistles provide some of the earliest documentary sources of women in the early Jesus movement.^[98][99] Female figures in early Christian art are ubiquitous.^[100] In church rolls from the second-century, there is conclusive evidence of groups of women "exercising the office of widow".^[101][102] Judith Lieu affirms that influential women were attracted to Christianity.^[103] Much of the vociferous anti-Christian criticism of the early church was linked to "female initiative" which indicates women were playing a significant role.^{[96][104][105][note 2]}

A key characteristic of these inclusive communities was their unique type of exclusivity.^[110] Believing was the crucial and defining characteristic of membership. Correct belief identified and separated believers from the "unbeliever" creating a high social boundary.^{[111][112][113]} Such exclusivity formed an important part of Christianity's success by enabling independence in a society that syncretized religion.^[113] In Daniel Praet's view, exclusivity gave Christianity the powerful psychological attraction of elitism.^[114]

Christian and non-Christian witnesses testify to the zealousness of Christian communities for almsgiving and charity.^[115] Christians showed the poor great generosity.^[116] Early Christianity redefined family by burying together church members not related by blood and extending funeral rites to include the Christian community.^[117][118] Christians had no sacrificial cult, and this set them apart from Judaism and the pagan world.^[119]

Constantine the Great became emperor in the West, declared himself a Christian, and in 313, two years after the close of Diocletian's persecution, issued the Edict of Milan expressing tolerance for all religions.^[120] The Edict was a pluralist policy, and throughout the Roman Empire of the fourth to sixth centuries, people shifted between a variety of religious groups in a kind of "religious marketplace".^{[121][122][123]}

Constantine supported and protected Christianity.^[124][122] He gave bishops judicial power and established equal footing for Christian clergy by granting them the same immunities polytheistic priests had long enjoyed.^[125] By intervening in church disputes, he initiated a precedent for ecclesiastical councils.^[126][127] Constantine was the first emperor to order the restoration of properties to the churches.^[128] Constantine devoted personal and public funds to building multiple churches, endowed his churches with wealth and lands, and provided revenue for their clergy and upkeep.^[129] There was a burst of church building under Constantine, and Christian art and literature blossomed.^[130] By the late fourth-century, there were churches in essentially all Roman cities.^[131]

Overt pagan-Christian religious conflict was once the dominant view of Late Antiquity.^[132] Twenty-first-century scholarship indicates that, while hostile Christian actions toward pagans and their monuments did occur, violence was not a general phenomenon.^{[133][134][135][note 3]} As Jan N. Bremmer writes, "religious violence in Late Antiquity is mostly restricted to violent rhetoric".^[137]

Popular support for the polytheistic religions had been declining since the second-century BC and continued to decline throughout Late Antiquity. Current scholarship indicates this is likely a result of economic factors more than Christianity. The economic crisis of the third-century had already produced a decline of urbanism and prosperity. Further economic disruption in the fourth and fifth-centuries occurred when various Germanic peoples sacked Rome and invaded multiple territories. Such disruption made fewer public funds and private donations available to support expensive pagan festivals and temples.^{[138][139][140]}

Constantine wrote a variety of hostile and discriminatory imperial laws aimed at suppressing sacrifice and magic and closing temples that continued their use.^[141] Blood sacrifice had been a central rite of virtually all religious groups in the pre-Christian Mediterranean, but it disappeared by the end of the fourth-century.^[142] This is "one of the most significant religious developments of late antiquity," writes Scott Bradbury, and "must be attributed to ...imperial and episcopal hostility".^[143]

Christian emperors wanted the empire to become a Christian empire, and they used imperial law to make it easier to be Christian and harder to be pagan.^{[144][145][146]} However, there was no legislation forcing the conversion of pagans until the sixth-century, during the reign of the Eastern emperor Justinian I, when there was a shift from generalized legislation to actions that targeted individual centers of paganism.^{[147][148][149]} Despite threatening imperial laws, occasional mob violence, and imperial confiscations of temple treasures, paganism remained widespread into the early fifth-century, continuing in parts of the empire into the seventh-century, and into the ninth-century in Greece.^[150][151]

Jews and Christians were both religious minorities, claiming the same inheritance, competing in a direct and sometimes violent clash.^[152] Augustine's ethic regarding the Jews rejected those who argued they should be killed or forcibly converted. Instead, he said Jews should be allowed to live in Christian societies and practice Judaism without interference because they preserved the teachings of the Old Testament and were "living witnesses" of the New.^[153] According to Anna Sapir Abulafia, scholars agree that "with the marked exception of Visigothic Spain in the seventh-century, Jews in Latin Christendom lived relatively peacefully with their Christian neighbors" until the 1200s.^[154][155]

Sometime before the fifth-century, the theology of supersessionism emerged, claiming that Christians had displaced the Jews as God's chosen people.^[156] Supersessionism was never official or universally held, but replacement theology has been part of Christian thought through much of history.^[157][158] Many attribute the emergence of antisemitism to this doctrine, while others make a distinction between supersessionism and modern antisemitism.^[159][160]

There has been a paradigm shift in modern scholarship that questions the existence of heresy and orthodoxy before the Council of Nicea (325) and differentiates heresy from schism.^[161]

The Church of Late Antiquity was seen by its supporters as a universal church.^[162][163] Membership was based on belief. Ancient authors used "correct belief" defined by apostolic tradition to identify all doctrinal variations and differing practices as heresy.^{[164][165][113][166]} The sheer number of laws directed at heresy in the fourth and fifth centuries indicate it was a much higher priority than paganism for Christians of this period.^[167][168]

In North Africa during the reign of Constantine, Donatism formed as a schism. Donatists refused - sometimes violently - to accept back into the Church those who had handed over sacred texts during Diocletian's persecution. After many appeals, the empire responded with force.^[169] In 408 in his Letter 93, Augustine defended the government's action.^{[169][170][note 4]}

Traditionally, scholars have seen Arianism as the great heresy of this period.^[25][172] Exactly what occurred has long been a matter of intense debate.^[173] Sometime around 320, Arius wrote a letter to his bishop, Alexander, distinguishing three distinct "substances" of God with the Father alone as eternal and not having a beginning. Contrary to traditional trinitarianism, the Son is not of the same substance as the Father in this metaphysic. Alexander responded by taking formal action against Arius and advising the wider church to do the same.^[174]

The First Council of Nicaea called by Constantine in 325 to resolve the controversy that resulted, produced a statement of orthodoxy in the form of the Nicene Creed. The First Council of Constantinople called by Theodosius I in 381, affirmed it.^[175][176]

The New Testament canon was eventually settled based on common usage.^[177] By the fourth-century, unanimity was reached in the Latin Church on which texts should be included.^[178] A list of accepted books was established by the Council of Rome in 382, followed by those of Hippo in 393 and Carthage in 397.^[179] For Christians, these became the New Testament, and the Hebrew Scriptures became the Old Testament.^[180] By the fifth-century, the Eastern Churches, with a few exceptions, had come to accept the Book of Revelation—and thus had come into harmony with the canon.^[181]

By Late Antiquity, the tendency for East and West to grow apart was already becoming evident.^[182] The Western church used Latin, while Eastern church leaders spoke and wrote in Greek, Syrian, and other languages. Theological differences were evident.^{[183][184][185]} In the Roman West, the church condemned Roman culture as sinful, tried to keep them separate, and struggled to resist State control (even though assimilation was still taking place). Eastern Christianity acclaimed harmony with Greek culture and upheld unanimity between church and state.^{[186][187][188]}

One particular bone of contention was Consantinople's claim of equal precedence with Rome.^[163] The East advocated Pentarchy, which would share the government of the church between the Patriarchs of Constantinople, Alexandria, Antioch, Jerusalem, and the Pope of Rome. First promoted through legislation of the emperor Justinian, and later confirmed by the Council in Trullo (692), the West opposed it, advocating instead for the papal supremacy of Rome.^[189][190]

Ongoing theological controversies over Jesus' human and divine natures as either one (or two) separate (or unified) natures led to the Third (431), Fourth (451), Fifth (583) and Sixth ecumenical councils (680–681).^[191] Schisms broke out after the Council of Chalcedon (451) wrote the Chalcedonian Definition that two separate natures of Christ form one ontological entity.^[192][193] Disagreement led the Armenian, Assyrian, and Egyptian churches to withdraw from Catholicism, and instead, combine into what is today known as Oriental Orthodoxy, one of three major branches of Eastern Christianity, along with the Church of the East in Persia and Eastern Orthodoxy in Byzantium.^{[194][195][196]}

In the Christian literature discussing sexuality from the second to the fifth centuries, there is tension between those who advocated for celibacy and those who advocated for marriage.^[197] Celibacy became mandatory for clerics in the Latin church, but not for Byzantines.^[198]

Christian monasticism was formerly thought to have begun as a fourth-century Egyptian phenomenon that spread to other regions. Twenty-first century scholarship asserts its origin was earlier in Syria where it emerged from the asceticism that had existed in Christianity from its beginning.^[199] Egyptian monasticism of the fourth and fifth centuries produced the texts and sayings, themes, and figures, that shaped much of modern understanding of monastics as "desert fathers".^[200] Palestine became a centre of pilgrimage and monastic communities were associated with the urban holy places. Monastics were in Cappadocia, Italy, Gaul and Roman North Africa.^[201] There were Greek and non-Greek communities in Jerusalem and Bethlehem.^[202]

In 358, Basil the Great founded a monastic community in Caesarea that developed an unprecedented health care system. It allowed the sick to be cared for in a special building at the monastery by those dedicated to their care giving the sick benefits which destigmatized illness. This transformed health care, formed the first public hospital in 369, and became a model for public hospitals into the twentieth-century.^[203]

For centuries after his death, Emperor Theodosius I (379-395) was regarded as the champion of Christian orthodoxy who stamped out paganism. Theodosius's predecessors had all been semi-Arians, and recent scholarship tends to see the ancient Christian writers as affirming orthodoxy rather than writing actual history.^{[204][205][206]} Scholars agree that Theodosius gathered a large amount of legislation on religious subjects, continued the practices of his predecessors against sacrifices, magic and temples that allowed them, issued multiple decrees against heretics, but did not see himself as a destroyer of the old cults.^{[207][205][208]}

Under Theodosius' direction, laws from different governors and emperors going back to Constantine were collected into the Theodosian Law Code. Originally written to resolve issues of a particular place and time, these laws often contradicted each other. Theodosius had them gathered together, organized by theme, and reissued throughout the empire between 389 and 391.^[209][210]

Constantine and his successors, attempted to fit the Church into their political program.^[211] Western church leaders resisted by making a case for a sphere of religious authority separate from state authority. Their objection forms the first clearly articulated limitation on the scope of a ruler’s power.^[212]

For most of Late Antiquity, the papacy had limited influence while the senatorial aristocracy played the central role. At the end of this period, the two powers began switching places.^{[213][214][215]} Patriarchs in the East frequently looked to the Pope to resolve disagreements resulting in the rise of papal power and influence.^[214][215]

After 476, despite the fragmentation of the empire and the absence of an emperor, the wealthy and independent Roman Senate remained vigorous and influential, even with the barbarians, playing an increasing role in church politics through the end of the fifth-century.^[216][217] In 535, the eastern emperor Justinian I (482 – 565) attempted to assert control over the Italian Peninsula in the Gothic war, which became a guerrilla war that lasted nearly 20 years. Surviving Roman senators, the pope, and the clergy of Rome looked forward to a period of reconstruction in the aftermath.^[218] Instead, in 554, Justinian asserted a Pragmatic Sanction that removed the Senate's support and effectively ended it as an institution.^[219] In 630, Pope Honorius I consecrated the Senate building Curia Julia as a church.^[220]

In the fourth-century, Constantine's sponsorship produced an exuberant burst of Christian art and architecture.^[221] Christianity developed its first normative public architecture modeled after a type of audience hall used by municipal courts. The basilica became the norm for, and the root of, all later types of Christian architecture.^[222]

A hybrid form of poetry written in traditional classic forms with Latin style and Christian concepts emerged. The Christian innovation of mixing genrés and new methods of interpreting history began.^{[223][224][225]} The codex (the ancestor of modern books) was consistently used by Christians as early as the first-century. The church in Egypt had most likely invented the papyrus codex by the second-century.^[226]

Around the year 400, art reflects optimism among traditional polytheists.^[227] This is likely connected to the revival of classical styles, overseen by Theodosius.^[228] The Theodosian Age (the last twenty years of the fourth century and the first twenty years of the fifth) has been described as "the last renaissance of the Roman Empire".^[228]

In the late fourth century, Pope Damasus I commissioned Jerome to translate the Greek biblical texts into the Latin language used by the educated governing classes. Called the Vulgate, it uses many terms common to Roman jurisprudence.^[229]

In the fourth and fifth centuries, church fathers wrote hundreds of works from different traditions, cultural contexts, and languages (i.e. Greek, Latin, Syriac, Ethiopian, Armenian, Coptic) contributing to what is generally understood to be the "Golden Age of Patristic Christianity".^{[230][215][231][232]} Augustine of Hippo, John Chrysostom, Gregory of Nyssa, Athanasius of Alexandria, Basil of Caesarea, Gregory of Nazianzus, Cyril of Alexandria, and Ambrose of Milan are among the many who made contributions to polemical works, orations, sermons, letters, poems, history, systematic theology, treatises on Christian doctrine, Biblical exegesis, scriptural commentary, and legal commentary.^[233]

Christianity grew rapidly and spread through the Empire into Western Europe and around the Mediterranean basin.^[32][234] In the fourth-century the Persian Empire had as high a percentage of Christians as the Roman Empire.^[235]

Climate change and economic factors drove the Huns out of inner Asia and across central Asia bringing pressure on the Persian Empire and both Eastern and Western Roman Empires.^[236] Ostrogoths migrated to Italy to escape them. Visigoths sacked Rome in 410 and eventually settled in Spain. Vandals crossed the Rhine and southern Gaul, moved into Spain and then Africa, playing a major role in the fifth-century. Many became Arian Christians.^{[237][238][239][240]}

Amid the rising, varied, and often warring barbarian kingdoms, Pope Leo I (440-461) created some unity for the western church through his forceful response to the decrees of the Council of Chalcedon, and his assertion of authority for the bishop of Rome.^[241]

In 397, Saint Ninian brought Christianity to Scotland.^[242]

The conversion of the Irish began in the early fifth-century through missionary activity and without coercion.^[243]

Christianity had become an established minority faith in some parts of Britain in the second-century.^[244] In the fifth century, migration led Anglo-Saxon forms of Germanic paganism to largely displace Christianity in south-eastern Britain.^[245] The Gregorian mission in 597 led to the conversion of the first Anglo-Saxon king Æthelberht around 600.^[246]

Irish missionaries went to Iona (563) and converted many Picts.^[247]

There is no consensus on the origins of Christianity beyond Byzantium in Asia or East Africa. Though it is scattered throughout these areas by the fourth-century, there is little documentation and no complete record.^[248] Asian and African Christians did not have access to structures of power, and their institutions developed without state support.^[249] Asian Christianity never developed the social, intellectual, and political power of Byzantium or the Latin West.^[79]

In 301, Armenia became the first country to adopt Christianity as its state religion. In an environment where the religious group was without cultural or political power, the merging of church and state is thought to represent ethnic identity.^[250] In the fourth century, Asia Minor, and Georgia forged national identities by adopting Christianity as their state religion, as did Ethiopia and Eritrea. In 314, King Urnayr of Albania adopted Christianity as the state religion.^{[251][252][253][254][85]}

In the central part of this period between the 600s and 750, (while Christianity still saw itself as universal), three distinct cultures emerged: in the West, Germanic Europe was beginning, and in the East, Byzantium and Islamic civilization were born.^[255][256]

In the last half of the fifth-century, cities in the western Roman Empire were in decline, streets were no longer being built, and fortifications were decaying.^[228] In Italy of 476, the Germanic king Odoacer deposed the last Roman emperor of the Western Empire.^[240] In Gaul in 496, Clovis I was baptized, became king of the Franks, and converted to Catholicism, turning Frankia into a kingdom when much of Western Europe was impoverished and politically fragmented.^[257] After 507, the Franks in Gaul were the dominant polity in the West.^[258]

The Franks effectively resisted Arabic inroads into southern France in 732.^[259] Charlemagne began the first Medieval Renaissance, the Carolingian Renaissance, a period of intellectual and cultural revival, in the 8th century. Renaissance continued through his descendants into the 9th century.^{[260][261][262]}

Christianity became dominant in England throughout the 7th century, during which suppression of Germanic paganism began. There are no recorded heathen kings after 954.^{[263][264][265][266]}

In this age, a great deal of diversity existed, yet the concept of Christendom was also becoming pervasive and unifying.^[267] Medieval writers and ordinary folk used the term to identify themselves, their religious culture, and even their civilization. Mixed within and at the edges of this largely Christian world, barbarian invasion, deportation, and neglect also produced large “unchurched” populations.^{[268][269][270]} In these areas, Christianity was often one religion among many and could combine with aspects of local paganism.^[263] Early medieval religious culture included "worldliness and devotion, prayer and superstition", but its inner dynamic sprang from a commitment to Christendom.^[267]

The means and methods of teaching a mostly illiterate populace included mystery plays (which had developed out of the mass), wall paintings, vernacular sermons and treatises, and saints' lives in epic form.^[267] Christian motifs could function in non-Christian ways, while practices of non-Christian origin became endowed with Christian meaning.^[271] From the sixth to the eighth centuries most schools were monastery-based.^[272]

Throughout this period, a symbiotic relationship existed between ecclesiastical institutions and civil governments. Canon law and secular law were connected and often overlapped.^[273] Canon laws, created by councils, kings, bishops, and lay assemblies, enabled the church to sustain itself as an institution and wield social authority with the laity.^[274] In the East, Roman law remained the standard. The West was a world of relatively weak states, endowed aristocracies, and peasant communities that could no longer use law from a "fallen" empire to uphold church hierarchy.^[275] Instead, the western church adopted a feudalistic oath of loyalty which became a condition of consecration.^[163]

The oath of loyalty between men and their king created a new model of consecrated kingship.^[276] Janet Nelson writes that:

This rite has a continuous history in both Anglo-Saxon England and Francia from the eighth-century onward, with further refinements in the ninth and tenth. It is, among other things, a remarkable application of law by early medieval churchmen in the West, to which the East offers no parallel.^[276]

During the sixth-century, monasticism flourished nearly everywhere Christianity existed. It developed somewhat differently in each region and by 600 there was great diversity, but monasteries still shared basic elements. Monastics followed a discipline of devotional practices aimed at cultivating an awareness of God which generally included formalized prayer, memorization of scripture, celibacy, fasting, manual labor, and almsgiving.^{[277][278][279][280][note 5]}

Monasteries became more and more organized from 600 to 1100.^[285] The formation of these organized bodies of believers gradually carved out social spaces with authority separate from political and familial authority, thereby revolutionizing social history.^{[286][note 6]} Medical practice was highly important, and medieval monasteries are best known for their contributions to medical care.^[299] For the majority of the faithful in the early Middle Ages of both East and West, the saint was first and foremost the monk.^[300]

Dedicated monks merged the Germanic practice of painting small objects and the classical tradition of fine metalwork to create "illuminated" psalters, collections of the Psalms, the gospels, and copies of the Bible. First using geometric designs, foliage, mythical animals, and biblical characters, the illustrations became more realistic in the Carolingian Renaissance.^[301]

In the 720s, the Byzantine Emperor Leo banned the pictorial representation of Christ, saints, and biblical scenes, destroying much of early art history. The West condemned Leo's iconoclasm.^[302] By the tenth and early eleventh centuries, Byzantine culture began to recover.^[303][304]

Popes led the sixth-century response to the invasion of northern Italy by the Lombards (569) producing an increase in papal autonomy and prestige.^[305] By the time Pope Gregory I succeeded to the papacy in 590, the claim of Rome's supremacy as stemming from Peter can be seen as established even though large sections of both the Western and Eastern churches remained unconvinced they should be submissive to the Roman See.^{[306][note 7]}

Papal power rose as competition within the church increasingly led people to Rome to resolve disagreements.^[163][312] The growing presence and involvement of the aristocracy in the papal bureaucracy, an increase in papal land-holdings from the second half of the sixth into the seventh-century, combined with changes in their administration that brought an increase in wealth, gradually shifted popes from being beneficiaries of patronage to becoming patrons themselves.^[313]

William IX, Duke of Aquitaine, and other powerful lay founders of monasteries, placed their institutions under the protection of the papacy in the tenth-century thereby facilitating another rise in papal power.^{[314][315][308]}

Byzantine culture blossomed during the reign of Emperor Justinian I.^[316] Justinian integrated Christian concepts with Roman law, creating the Code of Justinian.^[317] This code became an essential part of the Corpus Juris Civilis, which remains the basis of civil law in many modern states.^[318] Justinian made donations to the church, established foundations, and watched over church property. He supported the rights of bishops, priests, abbots, and monastic life. In 563, after earthquakes destroyed it, Justinian rebuilt the Hagia Sophia using ten thousand workers, and 40,000 pounds of silver, covering the dome in gold.^[319][320]

Justinian's religious policies reflected his conviction that the unity of the Empire presupposed unity of faith. He persecuted pagans and religious minorities and purged the governmental bureaucracy of those who disagreed with him.^[321][322] He regulated everything in religion and law, even interfering in papal elections.^[323][324] Manichaeism rose in southern Mesopotamia in the third-century and expanded from the fourth to sixth centuries in almost all parts of the Roman Empire, especially Syria, Mesopotamia, Egypt, North Africa and Italy.^[325] Severe persecution instigated by emperor Justinian ended them.^[326]

After the Age of Justinian (527–565) ended, the East was reduced in size, but it still had an emperor, its towns thrived, and taxes were still being collected. Its wealth, agriculture, sophisticated society, and theocracy allowed the Eastern Empire to become a Middle Eastern state, but it was war - with the Sassanids, the Slavs, and Islam - that forged it into the Byzantine Empire in the seventh-century.^[327][328]

In the early 600s, Christianity extended around the Mediterranean, across much of Europe into Spain and Britain, East to the edge of Central Asia as far as Zerang and Qandahar in modern Afghanistan, and into the Sassanian Persian Empire, with Christian churches concentrated in northern Iraq in the foothills of the Zagros, and in the trading posts of the Persian Gulf.^[329][330] A vibrant Asian Christianity with nineteen metropolitans (and eighty-five bishops), centred on Seleucia (just south of Baghdad), flourished in the eighth-century.^[331][332]

Two main kinds of Christian communities had formed in Syria, Egypt, Persia, and Armenia: urban churches which upheld the Council of Chalcedon, and Nestorian churches which came from the desert monasteries.^[333] Intense missionary activity between the fifth and eighth centuries led to eastern Iran, Arabia, central Asia, parts of China, and the coasts of India and Indonesia adopting Nestorian Christianity. The rural areas of Upper Egypt were all Nestorian. Coptic missionaries spread the Nestorian faith up the Nile to Nubia, Eritrea, and Ethiopia.^[334]

Born in the seventh century, Islamic civilization, in a series of Arabic military campaigns between 632 and 750, and diplomacy, conquered much of Syria, Mesopotamia, Egypt, Persia, North Africa, and Spain.^[335][336] By 635, upper-class Christian refugees had moved further east to China at Hsian-fu.^[337] Inferior legal status and persecution of non-Muslims eventually devastated the Chalcedonian churches in the cities. The monastic background of the Nestorians made their churches more remote, making them the most able to survive and cultivate new traditions.^[338][339]

The Middle Ages saw momentous changes in the economic and political structures of Europe and the inception of institutions that became fundamental to Christianity.^{[340][note 8]}

Membership in Christendom began with baptism at birth. Members were required to have a rudimentary knowledge of the Apostles' Creed and the Lord's Prayer. From peasant to pope, all were required to rest on Sunday and feast days, attend mass, fast at specified times, take communion at Easter, pay various fees, tithes, and alms for the needy, and receive last rites at death.^[346]

After 1054, the term Christendom did not include the Eastern churches. The Byzantine East and the Catholic West had long had many irreconcilable differences. Along with a general lack of charity and respect on both sides, there were also many cultural and linguistic differences, geographical separation, and geopolitical disagreements. In 1054, this produced the East–West Schism, also known as the "Great Schism", which separated the Church into Western Catholicism and Eastern Orthodoxy.^{[347][348][349]}

In the early part of this era, Viking raids and civil disorder destroyed many churches and monasteries inadvertently leading to reform and improvement. Patrons competed against each other in rebuilding, adding and improving, so that "by the mid-eleventh century, a wealthy, unified, better-organized, better-educated, more spiritually sensitive Latin Church" resulted.^[350]

Various reforms contributed.^[351] Gregorian Reform (1050–1080) increased papal power, centralized church authority, reinforced clerical celibacy, and established the College of Cardinals in 1150.^[352][353] Under Hugh of Cluny (1049–1109), the Abbey of Cluny became the leading centre of reform in Western monasticism from the eleventh into the early twelfth-century. The Cistercian movement, a second wave of reform after 1098, also became a primary force of technological advancement and its spread in medieval Europe contributing to economic growth.^{[354][355][356]}

Beginning in the twelfth-century, Mendicant orders (Franciscans and Dominicans) embraced a significant and impactful reformation in understanding a monk's calling as a charge to actively reform the world.^[357][358] The papacy recruited and licensed this new type of charismatic preacher whose purpose was to reform and correct an audience that was no longer the people of a parish or a city, but whole regions.^[359]

The Investiture controversy, which began in the Holy Roman Empire in 1078, was specifically a conflict between the Holy Roman Emperor Henry IV and Pope Gregory VII (1073–1085) over who had the right to invest a bishop or abbot into a paying job. More generally, it was over control of the church and its revenues.^{[360][361][362][363]}

Bishoprics were lifetime appointments, so a king could better control their powers and revenues than those of hereditary noblemen. He could place an aspirant of his choice, or leave the post vacant and collect the revenues himself, (theoretically in trust for a future bishop), or he could give a bishopric to compensate a helpful noble. For the church, ending this would better separate church from state, help with reform, and provide better pastoral care. For the civil authorities, ending lay investiture meant the power of the Holy Roman Emperor and the European nobility would be reduced.^{[364][185][365][309]}

Gregory recorded a series of statements asserting that the church must be the higher of the two powers of church and state and that the church must no longer be treated as a servant to the state.^{[315][366][367]} Disobedience to the Pope became equated with heresy.^[368] The Dictatus Papae of 1075 declared the pope alone could invest bishops.^[369] Henry IV rejected the decree. This led to his excommunication, which contributed to a ducal revolt, that led to a civil war: the Great Saxon Revolt. Eventually, Henry received absolution. The conflict lasted five decades.^{[370][371][372]} A similar controversy occurred in England.^[373]

King Alfonso VI of León and Castile captured Toledo in 1085. It was a major victory in the Christian overthrow of Islam in Spain, but the Almoravids prevented it from going further at that time.^[374]

In 1081 Alexios I Komnenos asked Pope Urban for help with the Seljuk Turks.^[375] Urban responded (1095) with an appeal to European Christians to "go to the aid of their brethren in the Holy Land".^{[376][377][378]} Urban's message had tremendous popular appeal, and there was much enthusiasm supporting it. It was new and novel and tapped into powerful aspects of folk religion. Voluntary poverty and its renunciation of self-will, along with a longing for the genuine "apostolic life," flourished in the late eleventh and twelfth centuries connecting pilgrimage, charity, remission of sins, and a willingness to fight.^{[379][380][note 9]}

Crusading involved the church in certain paradoxes: Gregorian reform was grounded in distancing spirituality from the secular and the political, while crusade made the church dependent upon financing from aristocrats and kings for the most political of all activities: war.^[382]

Crusades led to the development of national identities in European nations, increased division with the East, and produced cultural change.^[383] Hotly debated by historians, the single most important contribution of the Crusades to Christian history was, possibly, the invention of the indulgence.^[384]

The medieval papacy gained authority in every domain of life.^[385] With Pope Gregory VII, the scope of canon law was extended, and the church became a more imposing institution, consolidating its territory, and establishing a bureaucracy.^{[386][387][388]} Secular administrations were also centralizing and developing bureaucracies and competition (and emulation) between them developed into a battle-field of ideas and personalities. Both church and state claimed legal jurisdiction and the right to collect taxes from the same people. ^[340]

Popes from 1159 to 1303 were predominantly lawyers, not theologians.^[389] New networks and new agencies were often manifested as legal services, and over it all watched an increasingly centralized and proactive church government.^[388][390] Canon law became a large and highly complex system of laws that omitted Christianity's earlier principles of inclusivity.^{[317][391][392]} The papacy's power and influence gradually came to resemble that of the monarchs of its day.^{[385][393][note 10]}

Throughout Christian Europe, church and civic rulers made efforts to support coherence and order.^[396][397] Moral misbehavior and heresy, by the folk and clerics, were prosecuted by inquisitorial courts that were composed of both church and civil authorities.^[398] Bishops were in charge.^{[392][note 11]}

The Medieval Inquisition includes the Episcopal Inquisition (1184–1230) and the Papal Inquisition (1230s–1240s), though these courts had no actual joint leadership or organization.^{[402][403][404]} Created as needed, they were not permanent institutions but were limited to specific times and places.^{[399][405][406]}

Medieval inquisitors did not possess absolute power, nor were they universally supported.^{[398][note 12]} Riots and public opposition formed as inquisition became stridently contested both in and outside the Church.^{[399][408][409][note 13]}

In 1209, Pope Innocent III and the King of France, Philip Augustus, began a military campaign to eliminate the Albigensian heresy known as Catharism.^[412][413] Once begun, the campaign quickly took a political turn.^[414] The king's army seized and occupied strategic lands of nobles who had not supported the heretics, but had been in the good graces of the Church. Throughout the campaign, Innocent vacillated, sometimes taking the side favouring crusade, then siding against it and calling for its end.^[415] It did not end until 1229 when the region was brought under the rule of the French king, creating southern France, while Catharism continued for another hundred years (until 1350).^[416][417]

Traditionally, schools had been attached to monasteries. By the end of the eleventh century, Cathedral schools were established, and independent schools arose in some of the larger cities.^[418] For most folk, learning began at home, then continued in the parish where they had been born and were associated with for the rest of their lives.^{[340][note 14]} The clergy, and the laity, became "more literate, more worldly, and more self-assertive" and they did not always agree with the hierarchy.^[420]

Between 1150 and 1200, intrepid monks traveled to formerly Muslim locations in Sicily and Spain.^[421] Fleeing Muslims had abandoned their libraries, and among the treasure trove of books, the searchers found the works of Aristotle, Euclid and more. Adapting Aristotelian logical reasoning and Christian faith created a revolution in thinking called scholasticism which elevated reason and reconciled it with faith.^[422]

Scholasticism was a departure from the Augustinian thinking that had dominated the church for centuries. The writings of Thomas Aquinas are considered the height of scholastic thinking. His reconciliation of reason, law, politics, and faith provided the foundation for much modern thinking and law.^{[261][262][423][424]}

Renaissance also included the revival of the scientific study of natural phenomena. Historians of science see this as the beginning of what led to modern science and the scientific revolution in the West.^{[425][426][427]}

From the 1100s, Western universities, the first institutions of higher education since the sixth-century, were formed into self-governing corporations chartered by popes and kings.^{[428][429][430]} Bologna, Oxford and Paris were among the earliest (c. 1150). Divided into faculties which specialized in law, medicine, theology or liberal arts, each held quodlibeta (free-for-all) theological debates amongst faculty and students and awarded degrees.^[431][432] With this, both canon and civil law began to be professionalized.^[388]

This was a period of enormous creativity characterised by an imposing public Christian art full of light, colour, and rhythm.^[359] Romanesque style using Roman features with Christian influences, emerged in Europe between 1000 and 1200 as an aspect of the monastic revivals, especially the Cluniacs.^[351] It was used primarily in architecture but also produced statuary, paintings, and illustrated manuscripts.^[433]

Between 1137 and 1144 the Gothic style, with ribbed vaults and flying buttresses, such as those found in Notre Dame and the cathedral at Amiens, was invented.^[434]

The monk Guido of Arezzo modernized musical notation, invented the music staff of lines and spaces, and began the naming of musical notes making modern music possible.^[435][436]

By the end of the eleventh-century, Christianity was in full retreat in Mesopotamia and inner Iran. Some Christian communities further to the east continued to exist.^[439][440]

The Christian churches in Egypt, Syria, and Iraq became subject to fervently Muslim militaristic regimes.^[441] Christians were dhimma. This cultural status guaranteed Christian's rights of protection but discriminated against them through legal inferiority.^[339] Various Christian communities adopted different strategies for preserving their identity while accommodating their rulers.^[441] Some withdrew from interaction, others converted, while some sought outside help.^[441]

Christianization of Scandinavia (Sweden, Norway, and Denmark) occurred in two stages.^[442] In the first stage, missionaries arrived on their own, without secular support, in the ninth-century.^[443] Next, a secular ruler would take charge of Christianization in their territory. This stage ended once a defined and organized ecclesiastical network was established.^[444] By 1350, Scandinavia was an integral part of Western Christendom.^[445]

When the Second Crusade was called after Edessa fell, the nobles in Eastern Europe refused to go.^[446] The Balts, the last major polytheistic population in Europe, had been raiding surrounding countries for several centuries, and subduing them was what mattered most to the Eastern-European nobles.^{[447][note 15]} In 1147, Eugenius' Divina dispensatione gave eastern nobility indulgences for the first of the Baltic wars (1147–1316).^{[446][449][450]} The Northern Crusades followed intermittently, with and without papal support, from 1147 to 1316.^{[451][452][453]} Priests and clerics developed a pragmatic acceptance of the forced conversions perpetrated by the nobles, despite the continued theological emphasis on voluntary conversion.^[454]

In the second half of the eleventh century, three powerful groups – Seljuk Turks from the east, Almoravids from West Africa, and Crusaders from Europe – changed the politics, culture, and religious configurations of Byzantium, Islamic civilization, and the European West.^{[455][note 16]}

The Seljuk Turks triumphed in Anatolia (1071), and the Turkic Pechenegs raided the Balkans (1087). Emperor Constantine IX (r.1042–1055) turned to diplomacy welcoming the Pechenegs by administering baptism, conferring titles, and settling them in depopulated regions. Emperors at times welcomed the Turks in the same process.^[375]

Byzantium was weakened from repeated invasion, and its territorial frontiers became nebulous, but economically and spiritually the core of the Byzantine Empire of the eleventh and twelfth-centuries had never been more prosperous.^[397][304]

In April of 1204, western crusaders in the Fourth Crusade stormed, captured, and looted Constantinople.^{[461][462][463]} It was a severe blow.^[464] Byzantine territories were divided among the Crusaders establishing the Latin Empire and the Latin takeover of the Eastern church.^[465][466] By 1261, the Byzantines recaptured a much weakened and poorer Constantinople.^[467][468]

From the 950s to the 980s, polytheism among the Kievan Rus declined, while many social and economic changes fostered the spread of the new religious ideology known as Christianity.^[469] The event associated with the conversion of the Rus' has traditionally been the baptism of Vladimir of Kiev in 989.^[470]

The new Christian religious structure was imposed by the state's rulers.^[471] The Rus' dukes maintained control of the church which was financially dependent upon them.^{[472][note 17]} While monasticism was the dominant form of piety, Christianity permeated daily life, for both peasants and elites, who identified themselves as Christian while keeping many pre-Christian practices.^[474]

Beginning under emperor Basil I (r. 867–886), Byzantine Christianity was instrumental in forming what would become Eastern Europe.^[475][476] Serbia, Alania (modern Iran), Russia and Armenia were nascent Christian states by the early eleventh-century.^{[477][478][479]} Romania,^[480] Bulgaria,^[481] Poland,^[482] Hungary^[483][484] and Croatia soon followed.^[485]

Saints Cyril and Methodius translated the Bible, developing the first Slavic written script and the Cyrillic alphabet in the process. This became the educational foundation for all Slavic nations and influenced the spiritual, religious, literary, and cultural development of the entire region for generations.^{[469][486][487]}

A turning point in Jewish-Christian relations took place in June 1239 when the Talmud was put "on trial" by Gregory IX (1237–1241) in a French court over contents that mocked the central figures of Christianity.^[488][489] This resulted in Talmudic Judaism being seen as so different from biblical Judaism that old Augustinian obligations to leave the Jews alone no longer applied.^[490] As townfolk gained a measure of political power, they became one of Jewry's greatest enemies, charging Jews with blood libel, deicide, ritual murder, poisoning wells and causing the plague, and various other crimes.^{[491][492][359]} Although subordinate to religious, economic, and social themes, racial concepts also reinforced hostility.^[493]

Jews had often acted as financial agents for the lords providing them loans with interest while being exempt from taxes and other financial laws themselves. This attracted jealousy and resentment.^[494] Emicho of Leiningen massacred Jews in Germany in search of supplies, loot, and protection money. The York massacre of 1190 also appears to have had its origins in a conspiracy by local leaders to liquidate their debts along with their creditors.^[495]

The many calamities of the "long fourteenth-century" - plague, famine, multiple wars, social unrest, urban riots, peasant revolts, and renegade feudal armies – led folk to believe the end of the world was imminent.^{[496][497][498]} This belief ran throughout society and became intertwined with anticlerical and anti-papal sentiments.^{[499][359][note 18]} Attitudes and behaviours against the clergy identify the beginning of this period as a time of “anticlerical revolution".^{[501][note 19]} Intolerance is seen as one of the defining features of the Late Middle Ages.^{[503][504][505]}

Between 1300 and 1500, papal power stopped increasing, while kings continued to gain and consolidate power. A combination of events undermined the church's moral authority and constitutional legitimacy opening it to local fights of authority and control. Throughout this period, the church faced powerful challenges and vigorous political confrontations.^{[506][507][508][note 20]}

In 1309, Pope Clement V moved to Avignon in southern France in search of relief from Rome's factional politics. The Avignon Papacy consisted of seven popes whose residence there produced unintended consequences for the papacy. The move away from the "seat of Peter" caused great indignation throughout the church and cost popes prestige and power.^[515][516]

Pope Gregory XI returned to Rome in 1377.^{[517][518][497]} After Gregory's death, the papal conclave met in 1378, in Rome, and elected an Italian Urban VI to succeed Gregory. The French cardinals did not approve, so they held a second conclave electing Robert of Geneva instead, giving the church two popes. This began the Western Schism.^[519]

For the next thirty years the Church had two popes, then in 1409, the Pisan council called for the resignation of both popes, electing a third to replace them. Both Popes refused to resign, leaving the Church with three popes. Five years later, Sigismund the Holy Roman Emperor (1368-1437) pressed Pope John XXIII to call the Council of Constance (1414–1418) and depose all three popes. In 1417, the council elected Pope Martin V in their place.^[520][521]

Multiple strands of criticism of the clergy between 1100 and 1520 were voiced by clerics themselves. Such criticism condemned abuses and sought a more spiritual, less worldly, clergy.^[522] However, there is a constancy of complaint in the historical record that indicates most attempts at reform between 1300 and 1500 failed.^[523][524]

During the Late Middle Ages, groups of laymen and non-ordained secular clerics sought a more sincere spiritual life.^[525] A vernacular religious culture for the laity arose.^[380] The new devotion worked toward the ideal of a pious society of ordinary non-ordained people.^[526] Inside and outside the church, women were central to these movements.^[380]

During the European Renaissance of the 15th and 16th centuries, the Church was a leading patron of art and architecture, directly commissioning many individual works and supporting many artists such as Michelangelo, Brunelleschi, Bramante, Raphael, Fra Angelico, Donatello, and Leonardo da Vinci.^[527][528]

Scholars revealed the Donation of Constantine as a forgery.^[529]

Literature was impacted by Dutch scholar Desiderius Erasmus (1466 - 1536), an outstanding figure of Christian humanism in the sixteenth century. Meant to further reform the church, humanists taught a simplified faith accessible by any Christian who could pray directly to God for themselves.^[530]

The cult of chivalry evolved between the thirteenth and fifteenth centuries and became a true cultural force that influenced art, literature, and philosophy.^[531][532]

In 1439, a reunion agreement between the Eastern and Western churches was made. However, there was popular resistance in the East, so it wasn't until 1452 that the decree of union was officially published in Constantinople. It was overthrown the very next year by the Fall of Constantinople to the Ottoman Turks in 1453.^{[533][534][note 21]}

Compulsory resettlement returned many Greek Orthodox to Constantinople.^[536] While Islamic law did not recognize the Patriarch as a "juristic person", nor acknowledge the Orthodox Church as an institution, it did identify the Orthodox Church with the Greek community, and concern for stability allowed it to exist.^[537][538] The monastery at Mt. Athos prospered from the fourteenth to the sixteenth centuries.^[539] Ottomans were largely tolerant, and wealthy Byzantines who entered monastic life there were allowed to keep some control over their property until 1568.^[539]

Leaders of the church were recognized by the Islamic state as administrative agents charged with supervising its Christian subjects and collecting their taxes.^[540] Compulsory taxes, higher and higher payments to the sultan in hopes of receiving his appointment to the Patriarchate, and other financial gifts, corrupted the process and impoverished Christians.^[541][538] Conversion became an attractive solution.^{[542][note 22]}

Between 1478 and 1542, the modern Roman, Spanish and Portuguese inquisitions were created with a much broader reach than previous inquisitions.^{[544][545][546]}

The infamous Spanish Inquisition was responsible to the crown and was used to consolidate state interests.^[547] Authorized by the Pope in 1478, it was begun in answer to Ferdinand and Isabella's fears that Jewish converts (known as Conversos or Marranos) were spying and conspiring with Muslims to sabotage the new state.^[548][549] Of those condemned by the Inquisition of Valencia before 1530, ninety-two percent were Jews.^[550]

Initially, the Spanish Inquisition was so severe that the Pope attempted to shut it down. King Ferdinand is said to have threatened the Pope to prevent that.^{[551][552][553]} Five years after its inception, a papal bull conceded control of the Spanish Inquisition to the Spanish crown in October 1483.^[554][553] It became the first national, unified, centralized institution of the nascent Spanish state.^[555][547]

The Portuguese Inquisition was controlled by a state-level board of directors sponsored by the king who, during this period, was generally more concerned with ethnic ancestry than religion. According to Giuseppe Marcocci, there is a connection between the growth of the Inquisition and the statutes of blood purity.^[545] Anti-Judaism became part of the Inquisition in Portugal before the end of the fifteenth-century, and forced conversion led many Jewish converts to Portuguese colonies in India where they suffered as targets of the Goa Inquisition.^[556]

The Roman Inquisition operated to serve the papacy's long-standing political aims in Italy.^[557] The Roman Inquisition was bureaucratic, intellectual, and academic.^[558] It is probably best known for its condemnation of Galileo.^[559]

While the medieval Catholic church never advocated the full expulsion of Jews from Christendom, nor did the Church ever repudiate Augustine's doctrine of Jewish witness, canon law supported discrimination.^{[note 23]} Secular rulers repeatedly evicted Jews from their lands and confiscated Jewish property.^{[562][563][564]} In 1283, the Archbishop of Canterbury spearheaded a petition demanding restitution of usury and urging the Jewish expulsion in 1290.^[565][566]

Frankfurt's Jews flourished between 1453 and 1613 despite harsh discrimination. They were restricted to one street and were subject to strict rules if they wished to leave this territory, but within their community, they were allowed to maintain some self-governance. They had their own laws, leaders, and a well-known Rabbinical school that also functioned as a religious and cultural centre.^[563]

Powerful and pervasive ecclesiastical reform developed from medieval critiques of the church, but the institutional unity of the church shattered.^[567][568] Though there was no actual schism until 1521, the Protestant Reformation (1517–1648) has been described (since the nineteenth-century) as beginning when Martin Luther, a Catholic monk advocating church reform, nailed his Ninety-five Theses to the church door in Wittenberg in 1517.^[569]

Luther's theses challenged the church's selling of indulgences, the authority of the Pope, and various teachings of the late medieval Catholic church. This act of defiance and its social, moral, and theological criticisms brought Western Christianity to a new understanding of salvation, tradition, the individual, and personal experience in relationship with God.^[570] Edicts handed down by the Diet of Worms condemned Luther and officially banned citizens of the Holy Roman Empire from defending or propagating his ideas.^[571][572]

The three primary traditions to emerge directly from the Reformation were the Lutheran, Reformed, and the Anglican traditions.^[573] At the same time, a collection of loosely related groups that included Anabaptists, Spiritualists, and Evangelical Rationalists, began the Radical Reformation in Germany and Switzerland.^[574] Beginning in 1519, Huldrych Zwingli spread these teachings in Switzerland leading to the Swiss Reformation.^[575]

The Roman Catholic Church rebuked the Protestant challenge in what is called the Counter-Reformation or Catholic Reformation, spearheaded by a series of 10 reforming popes from 1534 to 1605, beginning with Pope Paul III (1534–1549).^[576] The Council of Trent (1545–1563) denied each Protestant claim, and laid the foundation of Roman Catholic policies up to the twenty-first-century.^[577] A list of books detrimental to faith or morals was established, the Index Librorum Prohibitorum, which included the writings of Protestants and those condemned as obscene.^[578]

New monastic orders were formed within the church, including the Society of Jesus - also known as the "Jesuits" - who adopted military discipline and a vow of loyalty to the Pope, leading them to be called "the shock troops of the papacy". They soon became the Church's chief weapon against Protestantism.^[577] Monastic reform also led to developments within orthodox spirituality, such as that of the Spanish mystics and the French school of spirituality.^[579] The Counter-Reformation also created the Uniate church which used Eastern liturgy but recognized Rome.^[580]

Religion became entangled with local politics when the quarreling royal houses, already involved in dynastic disagreements, became polarized into the two religious camps.^[581] Warfare initially broke out in the Holy Roman Empire with the minor Knights' War in 1522, then intensified in the First Schmalkaldic War (1546–1547) and the Second Schmalkaldic War (1552–1555).^[582][583] In 1562, France became the centre of religious warfare.^[584] The largest and most disastrous of these wars was the Thirty Years' War (1618–1648), which severely strained the continent's political system.^[585]

Theorists such as John Kelsay and James Turner Johnson argue that these wars were varieties of the just war tradition for liberty and freedom.^[586] William T. Cavanaugh identifies a view shared by many historians that the wars were not primarily religious, but were more about state-building, nationalism, and economics.^{[587][588][584]} Historian Barbara Diefendorf argues that religious motives were always mixed with other motives, but the simple fact of Catholics fighting Catholics and Protestants fighting Protestants is not sufficient to prove the absence of religious motives.^[589] According to Marxist theorist Henry Heller, there was "a rising tide of commoner hostility to noble oppression and growing perception of collusion between Protestant and Catholic nobles".^[590]

Until the 1300s, the official position of the Roman Catholic Church was that witches did not exist.^[591] While historians have been unable to pinpoint a single cause of what became known as the "witch frenzy", scholars have noted that, without changing church doctrine, a new but common stream of thought developed at every level of society that witches were both real and malevolent.^[592] Records show the belief in magic had remained so widespread among the rural people, that it has convinced some historians that Christianization had not been as successful as previously supposed.^[593] The main pressure to prosecute witches came from the common people, and trials were mostly civil trials.^[594][595] There is broad agreement that approximately 100,000 people were prosecuted, of which 80% were women, and that 40,000 to 50,000 people were executed between 1561 and 1670.^[596][592]

The conquest of 1453 effectively destroyed the Eastern Orthodox Church as an institution of the Christian empire as inaugurated by Constantine, sealing off Greek-speaking Orthodoxy from the West for almost a century and a half.^[597][598] The church was without one of its leaders, the Emperor, though it retained a patriarch in a lesser and more limited capacity.^[599] The Seljuq sultans and the Ottoman sultans were relatively tolerant, and this allowed the spiritual and cultural influence of the Eastern church, Constantinople, and Mount Athos the monastic peninsula to continue in slightly altered form among Orthodox nations.^[598] By the time of Süleyman the Magnificent (1520 – 1566), the patriarchate had become a part of the Ottoman system, and continued to influence the Orthodox world.^[543][538]

Jeremias II (1536 - 1595) dominated Eastern Christianity in the second half of the sixteenth century keeping Constantinople conservative and suspicious of Rome.^[600] Jeremias established contact with the new Protestant Lutherans, but nothing much resulted beyond Western Europeans becoming a little more aware of the problems of the church in captivity.^[600] Jeremias was the first Eastern patriarch to visit north-eastern Europe. Ending his visit in Moscow, he founded the Orthodox Patriarchate of Russia.^[600][538]

A generation after Constantinople fell to the Turks Ivan III of Muscovy adopted the style of the ancient Byzantine imperial court. This gained Ivan support among the late fifteenth and early sixteenth-century Rus elite who saw themselves as the New Israel and Moscow as the new Jerusalem.^[601] The Church reform of Peter I in the early eighteenth-century placed the Orthodox authorities under the control of the tsar. An ober-procurator appointed by the tsar ran the committee that governed the Church after 1721 until 1918: the Most Holy Synod. The Church became involved in the various campaigns of russification and contributed to antisemitism.^[602][603]

The era of absolutist states followed the breakdown of Christian universalism.^[604] Abuses from political absolutism practiced by kings supported by Catholicism, gave rise to a virulent anti-clerical, anti-Catholic, and anti-Christian sentiment that emerged in the 1680s.^[605] Critique of Christianity began among the more extreme Protestant reformers enraged by fear, tyranny, and persecution.^[606][607] Secularisation spread at every level of European society.^[608]

Beginning in the 1400s, Protestants steadfastly sought religious toleration for everyone including heresy, blasphemy, Catholicism, non-Christian religions, and even atheism.^[609] Anglicans and other Christian moderates also wrote and argued for toleration in the following centuries.^[610] In the 1690s, many secular thinkers were rethinking on a political level all of the State's reasons for persecution, and they also began advocating for religious toleration.^[611][612] Many treaties and political declarations of tolerance followed until concepts of freedom of religion, freedom of speech, and freedom of thought became established in most western countries.^{[613][614][615]}

In the early seventeenth-century, Baroque art, characterized by grandeur and opulence, offered the Catholic Church and secular rulers a means of expressing their magnificence and political power.^[616] This was a period of turmoil, discovery, and change, and Baroque art reflected the search for stability and order.^[617] It originated in Rome and became an international style. The church of St.Peter in Rome, St. Paul's cathedral in London, and the gardens at Versailles are probably the age's premiere examples.^[618]

Colonialism opened the door for Christian missions in many new regions.^{[619][620][621]} According to Sheridan Gilley "Catholic Christianity became a global religion through the Spanish and Portuguese colonial empires in the sixteenth-century and French missionaries in the seventeenth and eighteenth."^[620]

However, Christian missionaries and colonial empires had separate agendas that were often in direct opposition. Most missionaries avoided politics, yet over the last 500 years of missions, many vocal missionaries challenged colonial oppression, defended human rights, and opposed their own governments in matters of social justice. On the other hand, there are an equal number of examples of missionaries cooperating with colonial governments.^{[622][623][624]}

The sixteenth-century success of Christianity in Japan was followed by one of the greatest persecutions in Christian history. Sixteenth-century missions to China were undertaken primarily by the Jesuits.^[331][625] Sheridan Gilley writes that "The cruel martyrdom of Catholics in China, Indochina, Japan and Korea, another heroic missionary country, was connected to local fears of European invasion and conquest, which in some cases were not unjustified."^[626]

Historians often refer to the period from 1760 to 1830 as a "historical watershed" because it embraces the beginnings of the Industrial Revolution, the American Revolution, and the French Revolution.^[627]

In many cases, throughout this period, Christianity was weakened by social and political change.^[628] By the Nineteenth and Twentieth centuries, the influence of anticlerical socialism and communism produced secession and disruption in many locations.^[629]

After the Scientific Revolution (1600–1750), an upsurge in skepticism subjected all aspects of Western culture, including religious belief, to systematic doubt.^[630] Biblical criticism emerged (c. 1650 – c. 1800), pioneered by Protestants, using historicism and human reason to make the study of the Bible more scholarly, secular, and democratic.^{[631][632][633]} Depending upon how radical the individual scholar was, this produced different and often conflicting views, but it posed particular problems for the literal Bible interpretation which had emerged in the 1820s.^{[634][635][636]}

Before the Enlightenment of the eighteenth-century, liberalism was synonymous with Christian Idealism in that it imagined a liberal State that embraced political and cultural tolerance and freedom.^[635] Later liberalism embraced seventeenth-century rationalism, which was attempting to "wean" Christianity from its "irrational cultic" roots.^[637] This liberalism lost touch with the necessity of faith and ritual in maintaining Christianity which led to liberalism's decline and the birth of fundamentalism.^[638]

Fundamentalist Christianity arose in the late nineteenth and early twentieth-century as a reaction against modern rationalism.^[636] The Roman Catholic Church became increasingly centralized, conservative, and focused on loyalty to the Pope.^[633] Early in the twentieth-century, the Pope required Catholic Bible scholars who used biblical criticism to take an anti-modernist oath.^[633][639]

In the same period (1925), supporters of a relatively new, loosely organized, and undisciplined Protestant fundamentalism participated in the Scopes trial. By 1930, the movement appeared to be dying.^[640][641] Later in the 1930s, Neo-orthodoxy, a theology against liberalism with a reevaluation of Reformation teachings, began uniting moderates of both sides.^[642] In the 1940s, "new-evangelicalism" established itself as separate from fundamentalism.^[643]

Religious revival, known as the First Great Awakening, swept through the American colonies between the 1730s and the 1770s.^{[note 24]} Verbal battles over the movement raged at both the congregational and denominational levels creating divisions which became 'Parties', which turned political and eventually led to critical support for the American Revolution.^[648][649]

In places like Connecticut and Massachusetts, where one denomination received state funding, churches now began to lobby local legislatures to end that inequity.^[650] In 1791, the United States became the first predominantly Christian nation to mandate the separation of church and state. Theological pluralism became the new norm.^[651][652]

Scholars have identified a positive correlation between the rise of Protestantism and human capital formation,^[653] the Protestant work ethic,^[654] economic development,^[655] and the development of the state system.^[656] Max Weber says Protestantism contributed to the development of banking across Northern Europe and gave birth to Capitalism.^{[657][note 25]} However, the urbanization and industrialization that went hand in hand with capitalism created a plethora of new social problems.^[659][628] In Europe and North America, both Protestants and Catholics provided massive aid to the poor, supporting family welfare, medicine, and education.^[660]

France also experienced revolution, and by 1794, radical revolutionaries attempted to violently ‘de-Christianize’ France in what some scholars have termed a "deliberate genocidal policy of extermination" of Catholics in the Vendée region.^[661] When Napoleon came to power, he acknowledged Catholicism as the majority view and tried to make it dependent upon the state.^[662] For Eastern Orthodox church leaders, the French Revolution meant Enlightenment ideas were too dangerous to embrace.^[538]

The Second Great Awakening (1800–1830s) extolled moral reform as the Christian alternative to armed revolution. These reformers established nationwide societies, separate from any individual church, to begin social movements concerning abolition, women's rights, temperance and literacy.^[663] Developing nationwide organizations was pioneering, and many businesses adopted the practice leading to the consolidations and mergers that reshaped the American economy of the nineteenth-century.^[664] The second awakening produced the Latter Day Saint movement, the Restoration Movement and the Holiness movement.^[665]

Federal governments in the U.S. and Canada began boarding school systems to provide for the education and assimilation of Native Tribal peoples about 50 years before public school systems were instituted. Funded by the federal government, teachers were hired and schools were run by Catholics, Quakers, Methodists, Presbyterians, Episcopalians, and government representatives from the Indian Office, then the Indian Bureau, then the Bureau of Indian Affairs.^[666][667]

The majority of native children did not attend boarding school. In the earliest period, many were forcibly taken from their homes by the Federal government. Later, many were admitted in response to requests for education sent by native families to the Federal government. For Indigenous populations in Canada and the U.S., the history of boarding schools shows a continuum of experiences ranging from happiness and refuge to suffering, forced assimilation, mistreatment, abuse, and death. Over time, missionaries came to respect the virtues of native culture and spoke against national policies.^{[668][669][670][667]}

The Third Great Awakening began in 1857 and was most notable for taking the movement throughout the world, especially in English-speaking countries.^[665] Restorationists were prevalent in America. They have not described themselves as a reform movement but have, instead, described themselves as restoring the Church to its original form as found in the book of Acts. Restorationism gave rise to the Stone-Campbell Restoration Movement, Adventism, and the Jehovah's Witnesses.^[671][672]

For over 300 years, many Christians in Europe and North America participated in the Trans-Atlantic slave trade which had begun in the sixteenth-century.^[673] Moral objections had arisen immediately but had small impact.^[674] By the eighteenth-century, the Religious Society of Friends (Quakers), followed by Methodists, Presbyterians and Baptists, began to campaign, write, and spread pamphlets against the trade and slavery itself.^[675] In the years after the American Revolution, black congregations led by black preachers provided an institutional base for keeping abolitionism alive.^[676] By the early nineteenth-century, American Protestants had organized the first anti-slavery societies.^[677] According to historian David Eltis, the ideology of abolitionism eventually ended the Trans-Atlantic slave trade changing economic and human history on three continents.^[678][679]

Protestant missionaries had a significant role in shaping multiple nations, cultures, and societies.^{[626][76][680]} Women made major contributions.^[660] A missionary's first job was to get to know the indigenous people and work with them to translate the Bible into their local language. Approximately 90% were completed. Often, the process also generated a written grammar, a lexicon of native traditions, and a dictionary of the local language. These were used to teach in missionary schools resulting in the spread of literacy.^{[681][682][683]} Many native cultures responded with "movements of indigenization and cultural liberation."^{[684][685][681]}

The Bolsheviks and other Russian revolutionaries saw the Church, like the tsarist state, as an enemy of the people. Criticism of atheism was strictly forbidden and sometimes led to imprisonment.^[687][688] Some actions against Orthodox priests and believers included torture, being sent to prison camps, labour camps or mental hospitals, and execution.^[689][690]

Historian Scott Kenworthy describes the persecution of the Russian Orthodox Church under communism as "unparalleled by any in Christian history".^[691] In the first five years after the October Revolution, one journalist reported that 28 bishops and 1,200 priests were executed.^[692] Others report that 8,000 people were killed in 1922.^[693] The League of Militant Atheists adopted a five-year plan in 1932 "aimed at the total eradication of religion by 1937".^{[694][note 26]}

Despite oppression and martyrdom under hostile rule, the Orthodox churches of the twentieth-century continued to contribute to theology, spirituality, liturgy, music, and art. Kenworthy adds that "Important movements within the church have been the revival of a Eucharistic ecclesiology, of traditional iconography, of monastic life and spiritual traditions such as Hesychasm, and the rediscovery of the Greek Church Fathers".^[698]

In the early twentieth-century, European states were advocating the separation of church and state, while also establishing authoritarian governments and state-supported churches. Such consanguinity would, after 1945, implicate the church in abuses of power.^[699]

Pope Pius XI declared in Mit brennender Sorge (English: "With rising anxiety") that fascist governments had hidden "pagan intentions" and expressed the irreconcilability of the Catholic position with totalitarian fascist state worship which placed the nation above God, fundamental human rights, and dignity.^[700]

In Poland, Catholic priests were arrested and Polish priests and nuns were executed en masse.^[701]

Most leaders and members of the largest Protestant church in Germany, the German Evangelical Church, which had a long tradition of nationalism and support of the state, supported the Nazis when they came to power.^[702] A smaller contingent, about a third of German Protestants, formed the Confessing Church which opposed Nazism.^{[note 27]}

Nazis interfered in The Confessing Church's affairs, harassed its members, executed mass arrests, and targeted well-known pastors like Martin Niemöller and Dietrich Bonhoeffer.^{[704][705][note 28]} Bonhoeffer, a pacifist, was arrested, found guilty in the conspiracy to assassinate Hitler, and executed.^[707]

After World War II, Christianity became a global religion, faced major challenges, broke down denominational boundaries, was impacted by war, and gave substantive aid to the oppressed.^[708] Within these five areas, the papacy, ecumenical movement, missionary movement, Pentecostal movement, and individualistic independence have had international significance.^[709]

The world's largest religion has been Christianity since the eighteenth-century.^[620] Before 1945, about a third of the people in the world were Christians (with about half of those Roman Catholic), and about 80% of all Christians lived in Europe, Russia, and the Americas.^[711] After the collapse of communism in Eastern Europe and Russia, Christianity grew and expanded there and spread in Africa and Asia. By 2000, the percentage of Christians in the West dropped to around 40 percent, while the proportion living in Asia and Africa rose to 32 percent.^[711] Christianity's population center shifted east and south, making it a truly global religion.^[620][651]

In the first quarter of the twenty-first century, most Christians live outside North America and Western Europe. White Christians are a global minority, and slightly over half of worldwide Christians are female.^[712][713] It remains the world's largest religion into the twenty-first-century with roughly 2.4 billion followers, constituting around 31.2% of the world population.^{[620][651][714]}

In 1900, under colonial rule, there were just under 9 million Christians in Africa. By 1960, and the end of colonialism, there were about 60 million. By 2005, African Christians had increased to 393 million, about half of the continent's total population.^[682] Population in Africa has continued to grow with the percentage of Christians remaining at about half in 2022.^[710] This expansion has been labeled a "fourth great age of Christian expansion".^{[715][note 29]}

Christianity has grown rapidly in China and the rest of Southeast Asia, especially Korea, where it grew faster after colonialism than before it.^{[720][721][722]} A rapid expansion of charismatic Christianity began in the 1980s, leading Asia to rival Latin America in the population of Charismatic and Pentecostal Christians.^[723][724] The Council on Foreign Relations data shows a 10% yearly growth in Chinese Christian populations since 1979. Increasingly, this includes young people more than any other group.^{[725][726][727]}

Traditional Christianity has faced multiple challenges in the twentieth-century.^[728] In the U.S., Pew has reported that "As recently as the early 1990s, about 90% of U.S. adults identified as Christians. But [in 2015], about two-thirds of adults are Christians".^[729][730] Secularism, the changing moral climate in the West, and various types of political opposition have led to a decline in church attendance.^[731][624] Hugh McLeod writes that,

The most powerful and effective criticism of Christianity in the twentieth-century has been the charge that it has been too closely identified with the rich and powerful, and too ready to legitimate the status quo. These political criticisms have had a far wider impact than those deriving from scientific or philosophical objections to religion.^[732]

Highly authoritarian and totalitarian governments have brought about crises and decline in churches in many areas.^{[728][624][733]} From 1945 into the 1980s, the world's first Marxist super-power, along with the many other communist governments, pursued anti-religious policies that were often violent.^[699] In 2013, 17 Muslim majority states reported 28 of the 29 types of religious discrimination against 45 of the 47 religious minorities in their countries, including Christianity.^[734] Anti-Christian persecution has become a consistent human rights concern.^[735]

The challenges of secularism, and the changing moral climate of the 1960s and 1970s, caused controversy within the churches concerning sexual ethics, gender, and exclusivity.^[731] A growing demand for greater individual freedom led to new forms of religion that embrace the sacred as a deeper understanding of the self.^[736] This "New Age" spirituality is private and individualistic and differs radically from Christian tradition, dogma, and ritual.^[737][738]

The Prosperity gospel formed as an adaptation of Pentecostalism. It challenges traditional Christianity because it has moved away from the Reformation view of biblical authority to the authority of personal charisma.^[739] Begun in the twentieth-century's last decades, it has become a trans-national movement.^{[740][note 30]} In 2000, approximately one-quarter of all Christians worldwide were part of Pentecostalism and its associated movements.^[742] By 2025, Pentecostals are expected to constitute one-third of the nearly three billion Christians worldwide making it the largest branch of Protestantism and the fastest-growing religious movement in global Christianity.^[743][744]

Collaboration between Protestants and Catholics made little progress until 11 October 1962, when Pope John XXIII opened the Second Vatican Council, the 21st ecumenical council of the Catholic Church.^[745][746] On 21 November 1964, the Second Vatican Council published Unitatis Redintegratio, stating that Roman Catholic ecumenical goals are to establish full communion amongst all the various Christian churches including Protestants.^[747][748] Amongst Evangelicals, there is no agreed-upon definition, strategy, or goal for ecumenism.^[749] Different theologies on the nature of the Church have produced some hostility toward it instead.^[750][751]

While the sentiment is widespread that ecumenism at the upper levels of leadership has stalled, the trend at the local level has been toward discussion and prayer meetings, pulpit exchanges, and shared social action.^[752][746] The common threat of secularisation and a recognition of the destructive potential of religious hatred has encouraged cooperation between churches.^[753] In the U.S. there has been an increase in inter-marriage. Almost 40% of couples married since 2010, compared to 19% before 1960, have married someone outside of their faith, according to Pew Research Center.^[754]

Christianity is still diverse, and Christians still disagree, but the grounds have changed to topics that engage the deepest and most controversial issues of the twenty-first-century - "race, gender, colonialism, and liberation" - bringing these to the forefront of the larger more traditional Christian agenda.^[755][756] In Hugh MacLeod's view, "A liberal Catholic is likely to have a lot in common with a liberal Methodist", and this commonality is only likely to increase with the influence of the internet.^[756]

The multiple wars of the twentieth-century brought questions of theodicy to the forefront.^[757] Wars have had contradictory effects on the church, sometimes producing a loss of faith in human solutions, an upsurge in religiosity and patriotism, or an alienation from Christianity.^[757] For the first time since the pre-Constantinian era, Christian pacifism became an advocated Christian option to war in the twentieth-century.^[732]

The nineteenth-century revolutions that established Orthodoxy in the Serbian, Greek, Romanian, and Bulgarian nations were changed in the twentieth-century from a universal church into a series of national churches that became subordinate to nationalism and the state.^[538]

Liberation theology has been especially effective in aiding the Latin American poor.^[758] To redeem the institutions of society using the "kingdom ideals" from Jesus' Sermon on the Mount, the Social Gospel combined with liberation theology to redefine social justice, focus on the community's sins, and expose institutionalized sin.^{[759][760][761]}

Originating in America in 1966, Black theology developed a combined social gospel and liberation theology that mixes Christianity with questions of civil rights, aspects of the Black Power movement, and responses to black Muslims claiming Christianity was a "White man's" religion.^[762] Spreading to the United Kingdom, then parts of Africa, confronting apartheid in South Africa, Black theology explains Christianity as liberation for this life not just the next.^{[762][763][note 31]}

The feminist movement of the mid to late twentieth-century began with an anti-Christian ethos but soon developed a significant and influential Feminist theology dedicated to transforming the churches and society.^[766][767] In the last years of the twentieth-century, the re-examination of old religious texts through diversity, otherness, and difference developed womanist theology of African-American women, the "mujerista" theology of Hispanic women, and insights from Asian feminist theology.^[768]

After World War II, Christian missionaries played a transformative role in many colonial societies, moving them toward independence through decolonization.^[769][770] In the mid to late 1990s, postcolonial theology emerged globally from multiple sources.^[771] It analyzes structures of power and ideology to recover what colonialism erased or suppressed in indigenous cultures.^[772]

According to historian Lamin Sanneh, Protestant missionaries began the "largest, most diverse and most vigorous movement of cultural renewal in history" in Africa.^{[773][774][624]}

The missionary movement of the twenty-first-century has transformed into a multi-cultural, multi-faceted global network of NGO's, short-term amateur volunteers, and traditional long-term bilingual, bicultural professionals who focus on evangelism and local development and not on 'civilizing' native people.^[775][776]

• Catholic Church and Nazi Germany
• Celtic Christianity
• Christianization of Kievan Rus'
• Christianity and Judaism
• Christianity in Asia
• Christianity in Egypt
• Christianity in Syria
• Chronicle of Arbela
• Chronology of early Christian monasticism
• Chronology of Jesus
• Cluniac Reforms
• Criticism of Christianity
• Donation of Pepin
• Dutch Reformed Church
• English Benedictine Reform
• Frankish Papacy
• Germanic Christianity
• Hellenistic Judaism
• Historical background of the New Testament
• Historical Jesus
• Historiography of Christianization of the Roman Empire
• History of Calvinism
• History of Christianity of the Late Modern era
• History of Christian universalism
• History of the Eastern Orthodox Church
• History of Oriental Orthodoxy
• History of Protestantism
• History of the Catholic Church
• History of the Eastern Orthodox Church under the Ottoman Empire
• Pope Pius XII and the Holocaust
• Positive Christianity
• Religion in the Soviet Union
• Religious policies of Constantius II
• Rise of Christianity during the Fall of Rome
• Timeline of Christian missions
• Timeline of the Roman Catholic Church

Christian history
BC	C1	C2	C3	C4	C5	C6	C7	C8	C9	C10
C11	C12	C13	C14	C15	C16	C17	C18	C19	C20	C21