Christianity
Some of these groups could not agree on certain points about Christian teaching (called “doctrine”) or practice. The first split was in the 5th century after the Church Council of Ephesus. The council agreed Nestorianism was wrong. The Assyrian Church of the East did not agree and split from the rest. The argument was about the nature of Jesus. Should he be regarded as God and human in one combined nature, or in two separate natures? Most of the bishops, following the Pope (the Bishop of Rome), refused to stay in communion with any bishop who would not say "two separate natures". This was also discussed at the Council of Chalcedon, about 20 years later. The Christians who did not agree with the decision of the Council to excommunicate them, became the non-Chalcedonian Orthodox. The largest Non-Chalcedonian Churches are the Coptic Orthodox in Egypt, the Ethiopian Orthodox, the Armenian, and some Lebanese Orthodox Churches. In general, these churches are known as Oriental Orthodox Churches. Recent discussions between the Roman Catholic Pope John Paul II and the Coptic Orthodox Pope Shenouda III concluded that they believe many of the same things after all, even though the Coptic Church does not recognize the Pope of Rome as its leader.