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Ancient apostolic churches

The oldest lasting schism in Christianity resulted from fifth-century disagreements on Christology, heightened by philosophical, linguistic, cultural, and political differences.

The first significant, lasting split in historic Christianity, the so-called Nestorian Schism, came from the Church of the East, consisting largely of Eastern Syriac churches outside the Roman Empire, who left full communion after 431 in response to misunderstandings and personality conflicts at the Council of Ephesus. After fifteen centuries of estrangement, the Assyrian Church of the East and the Catholic Church entered into an ecumenical dialogue in the 1980s, resulting in agreement on the very issue that split them asunder, in the 1994 Common Christological Declaration, which identifies the origin of the schism as largely linguistic, due to problems of translating very delicate and precise terminology from Latin to Aramaic and vice versa.

As part of the then-ongoing Christological controversy, following the Council of Chalcedon in 451, the next large split came with the Syriac and Coptic churches dividing themselves. The churches dissented from Chalcedon, becoming today's Oriental Orthodox Churches. These also include the Armenian Apostolic Church, the Ethiopian Orthodox Tewahedo Church, and the Malankara Orthodox Syrian Church in India. In modern times, there have also been moves towards healing this division, with common Christological statements being made between Pope John Paul II and Syriac patriarch Ignatius Zakka I Iwas, as well as between representatives of both Oriental Orthodoxy and the Eastern Orthodox Church.