The History of Christianity — From a Jewish Sect to the World's Largest Religion
The two-thousand-year trajectory of the faith that began as a persecuted Jewish movement in Roman Palestine, became the religion of empires, split repeatedly over doctrine and authority, spread across the globe through missions and colonization, with growth concentrated in the Global South in the modern era.
Events
The Crucifixion and the Resurrection Proclamation
Jesus of Nazareth, an itinerant Jewish preacher, was crucified in Jerusalem under Roman authority around AD 30-33. His followers proclaimed that he had risen from the dead and was the incarnation of God — the claim on which the movement was built. Within decades, communities of his followers existed across the eastern Mediterranean as a largely urban, grassroots movement.
Location: Jerusalem, Roman Judea
The Edict of Milan
After centuries in which Christians were sporadically persecuted — most intensely under Diocletian — Emperor Constantine issued the Edict of Milan with co-emperor Licinius, legalizing Christianity across the Roman Empire. Constantine's own conversion and later patronage transformed a persecuted sect into an imperial religion.
Location: Milan, Roman Empire
The Council of Nicaea
Constantine summoned bishops to Nicaea to settle the dispute over whether Christ was of the same substance as God, a position championed by Athanasius against Arius's teaching that the Son was created. The council produced the Nicene Creed, but Arian and other doctrinal disputes continued for centuries, and the creed's enforcement involved both theology and imperial politics.
Location: Nicaea, Roman Empire
The Fall of Rome and Augustine's City of God
When Visigoths sacked Rome in 410, critics blamed the abandonment of the old gods. Augustine of Hippo responded with "The City of God" (413-426), framing history as a struggle between two cities — the earthly and the divine — and giving Christianity a theology that could survive the empire's collapse. As the Western Empire fell, monasteries became preservers of literacy, learning, and social services.
Location: Rome, Western Roman Empire
The East-West Schism
Centuries of divergence over papal authority, the filioque clause, liturgy, and political separation between Rome and Constantinople culminated in mutual excommunications between the papal legate and the Patriarch of Constantinople in 1054. The split formally separated Eastern Orthodoxy from the Catholic Church — a division that has never been healed.
Location: Constantinople, Byzantine Empire
The Crusades
Pope Urban II called for a military expedition to aid the Byzantine East against the Turks and secure Jerusalem, launching the Crusades. The movement fused pilgrimage, warfare, and papal authority for two centuries. Chronly's full Crusades story (1096-1291) covers the campaigns in detail.
Location: Clermont, France
The Reformation
Martin Luther's 95 Theses against the sale of indulgences ignited the Protestant Reformation, fracturing Western Christendom. Luther's stated aim was reform of corruption; Rome saw heresy. The resulting wars of religion reshaped Europe, and new doctrines — Lutheranism, Calvinism, Anglicanism — permanently ended the Catholic Church's western monopoly. Chronly's full Reformation story (1517-1648) covers the era.
Location: Wittenberg, Germany
The Edinburgh Missionary Conference
Some 1,200 Protestant delegates gathered in Edinburgh for the modern missionary movement's landmark conference, aiming to "evangelize the world in this generation." The era of missions spread Christianity — along with schools, hospitals, printing, and colonial administration — across Africa and Asia, laying the linguistic and institutional foundations of many modern churches. Missionary Christianity was both entangled with European colonialism and, in many colonies, a source of indigenous leadership and eventual nationalism.
Location: Edinburgh, Scotland
The Second Vatican Council
Pope John XXIII convened Vatican II, which in four sessions reshaped Catholic practice: the Mass was translated into local languages, the laity's role expanded, and the Church formally declared respect for other religions and religious liberty. The reforms energized some Catholics and provoked traditionalist resistance — schisms and disputes over the council's implementation continue within Catholicism.
Location: Vatican City
The Global South Becomes Christianity's Center
By the early twenty-first century Christianity counted over two billion adherents and was the world's most widely practiced religion, but its demographic center had shifted decisively to Africa, Asia, and Latin America. Europe and North America saw sustained decline in church attendance and religious affiliation, while Pentecostal and evangelical churches grew rapidly in the Global South — reversing the historical north-to-south direction of missionary expansion.
Location: Global