Christianity and Its Branches

Christianity began among the followers of Jesus of Nazareth, crucified in Jerusalem in c. 30 CE by Britannica’s dating. In 2020 it was the largest religion, with 2.27 billion adherents, 28.8% of the world, by the Pew Research Center’s estimate; the World Christian Database counts 2.52 billion for the same year, a difference set out in the overview. This part traces the faith’s spread and branches and where its adherents now live. The Latter-day Saint movement, founded in 1830, is covered in a separate study of Mormonism.

From Jerusalem to the empires

Britannica dates Armenia’s adoption of Christianity to about 300 CE; Mark Cartwright, writing for World History Encyclopedia in 2018, reports that modern historians prefer about 314. The Council of Nicaea met in 325. Emperor Theodosius I issued the Edict of Thessalonica on February 28, 380, and the Aksumite king Ezana, in what is now Ethiopia and Eritrea, converted around 340–356 CE, according to Smarthistory.

The branches

The families of churches that exist now trace their separations to dated events. The Council of Ephesus condemned the teaching of Nestorius in 431; the churches now called Oriental Orthodox did not accept the definition of the Council of Chalcedon of 451, in the words of CNEWA, the Catholic agency for the Eastern churches. The pope and the patriarch of Constantinople excommunicated each other in 1054. Martin Luther’s Ninety-five Theses are dated October 31, 1517; the first Anabaptist adult baptism probably January 21, 1525; the Act of Supremacy, which made Henry VIII head of the Church of England, 1534; John Smyth’s first Baptist church 1609; John Wesley’s conversion, which Britannica’s article on Methodism dates to May 24, 1738; and the Azusa Street revival in Los Angeles, the starting point Britannica gives for Pentecostalism, 1906 (Exhibit 10).

The move south

In 1900 about four of every five Christians lived in Europe and Northern America, by the World Christian Database. By 2025 the Global South held 68.9% of them. Africa’s Christians numbered 9.6 million in 1900 and 754 million in 2025; Europe’s, counted with Russia, were highest in 2020 among the years published, 567 million, and are projected to fall to 474 million by 2050 (Exhibit 11). Pew’s figures show the same shift on a shorter run: sub-Saharan Africa passed Europe as home to the most Christians between 2010 and 2020, with 30.7% of the world’s Christians against 22.3%, according to its 2025 report.

Of the four traditions Gordon-Conwell counts, Catholics were the largest in 2025, 1.27 billion. Between 1900 and 2025 Catholics multiplied 4.8 times, Protestants 4.7 times and Orthodox 2.5 times. Independents, Gordon-Conwell’s term for churches that do not identify with the historic denominations, rose from 8.9 million in 1900 to 409 million; Pentecostals and Charismatics from 981 thousand to 664 million (Exhibit 12).

Where Christians live now

The ten countries with the most Christians in 2020 included four in Africa. Between 2010 and 2020 the number fell by 26.2 million in the United States and rose by 26.2 million in the Democratic Republic of the Congo and 18.8 million in Nigeria, in Pew’s counts (Exhibit 14).

Christians were a majority in 124 countries and territories in 2010 and 120 in 2020. The four that changed were the United Kingdom, Australia, France and Uruguay; in each, Pew reports, the unaffiliated now make up 40% or more of the population (Exhibit 15). In the United States the Christian share fell from 78.3% to 64.0% in the same estimates.