List of Christian denominations by number of members

Christianity arose in the first century AD after Rome had conquered much of the western parts of the fragmented Hellenistic empire created by Alexander the Great.

The linguistic and cultural divisions of the first century AD Roman Empire with, broadly speaking, a Latin West and a Greek East, but also with significant areas in North Africa where Coptic was the dominant language, and areas in the Near East where Syriac or Aramaic was the dominant language, were reflected in the early Christian church.

The church was called "Catholic" meaning "universal" from very early in the second century, a tacit acknowledgement of the many different cultures it encompassed.

The Church chose to address those disputes with Ecumenical councils, the first four of which were at Nicaea, Constantinople, Ephesus and Chalcedon.

A few decades later, in 451 AD, after the Council of Chalcedon, the group that later became known as the Oriental Orthodox Churches, encompassing many Coptic speaking Christians in North Africa, also split off.

In 1054 AD, an accumulation of misunderstanding, disrespect and genuine theological differences led to the Great Schism, dividing Greek speaking Christians who became the Eastern Orthodox, from Latin speaking Christians who kept the name Catholic, but increasingly prefaced it with the adjective "Roman".

Beginning in 1517, the remaining western, Latin speaking church was itself rent asunder by the Reformation with many Christians rejecting papal authority and gathering together in new ways.

While all of these Christian groups from the Church of the East on, have their own subsequent splits, the fragmentation in Protestantism has been extreme, with tens of thousands of denominations.

Some of these fragmented groups, particularly among the Eastern churches, have sought to return to Rome, and have reunited themselves under papal authority.

[19][20][21][22][23][24][25][26][27] The main reason for this wide range is the lack of a common agreement among scholars as to which denominations constitute Protestantism.

For instance, most sources include Anabaptism, Anglicanism, Baptists and non-denominational Christianity as part of Protestantism.

[28][29] Moreover, Protestant denominations altogether do not form a single structure comparable to the Catholic Church, or to a lesser extent the Eastern Orthodox communion.

Note that this 900 million figure also includes Anglicans, Anabaptists, Baptists, as well as multiple other groups that might sometimes disavow a common "Protestant" designation, and would rather prefer to be called, simply, "Christian".

Instead, they are broadly linked to Pentecostalism or similar other independent evangelical and revivalistic movements that originated in the beginning of the 20th century.

[223][21][22] Despite the absence of centralized control or leadership, if considered as a single cohort, this will easily be the second largest Christian tradition after Roman Catholicism.