Although there is only one universal Christian Church, there are tens of thousands of Christian branches of Christianity. These branches of Christianity are referred to as denominations. These denominations have formed and divided since the time of Christ, because Christians have had differences in beliefs and practices. Some of the main groups include Eastern Orthodoxy, Roman Catholicism and the Protestant churches and Pentecostal churches.
The Roman Catholic Church is a major Christian denomination. It's head-quarters are in Rome but it has congregations throughout the world. It claims to have an unbroken leadership first from Jesus Christ, through the apostle Peter to the pope by Apostolic Succession.
The Eastern Orthodox Church is a body of Christians that claims origins extending directly back to Jesus and his Apostles through unbroken Apostolic Succession. Its doctrines were formalized through a series of church councils in the following centuries. Toward the end of its first thousand years of existence differences developed between the Church in the Eastern and Western Roman Empire that ultimately led to the Great Schism in 1054 dividing Christianity into Roman Catholicism and Eastern Orthodoxy. Today the Eastern Orthodox Church includes the the various national churches of Eastern Europe such as the Greek Orthodox and Russian Orthodox churches, and maintains a strong presence in these ethnic communities in countries such as the United States and Australia.
The Oriental Orthodox Communion refers to the churches of Eastern Christian traditions that keep the faith of only the first three ecumenical councils and reject the the Council of Chalcedon. Thus, despite potentially confusing nomenclature, Oriental Orthodox churches are distinct from the churches that collectively refer to themselves as Eastern Orthodoxy. The Oriental Orthodox churches came to a parting of the ways with the remainder of Christianity in the 5th century. The separation resulted in part from the Oriental Orthodox churches' refusal to accept the view that Jesus has two natures — one divine and one human. The Oriental Churches include the Armenian Apostolic Church, Coptic Orthodox Church and the Syrian Orthodox Church.
The Holy Apostolic and Catholic Assyrian Church of the East is a church that traces its origins to the See of Babylon, said to be founded by the apostle Thomas. It is also called the Assyrian Orthodox Church, but should not be confused with the distinct Syriac Orthodox Church, which belongs to Oriental Orthodoxy. Its geographical origins lie in Iraq and Iran and it onced stretched to Xian in China and Kerala in India. It officially divided from the other Christian churches in 431 AD following the Council of Ephesus which repudiated Nestorianism and as such it is often known as the Nestorian Church, however its theology is not strictly Nestorian. Today there are about 5 million members of the church, of which most live in Iraq, Iran, Syria and Lebanon.
Protestantism is a movement within Christianity, representing a split from the Roman Catholic Church that occurred during the sixteenth century in Europe — a period known as the Protestant Reformation. The split occurred primarily over issues of doctrine, especially the issue of Justification by faith versus Justification by faith plus works. Some of the main Protestant church denominations today include the Lutheran Church, Anglican Communion and the Baptist Church.
The Pentecostal movement within Christianity places special emphasis on the gifts of the Holy Spirit, especially talking in tongues. Some Pentecostals believe that belief in Christ and salvation is always accompanied initially by the outward evidence of speaking in tongues. Some of the main Pentecostal denominations today include the Assemblies of God, the Church of God in Christ and the Pentecostal Assemblies of the World.