in 325, the First Council of Constantinople in 381 and the Council of Ephesus in 431. Oriental Orthodoxy shares much theology and many ecclesiastical traditions with the Eastern Orthodox Church; these include a similar doctrine of salvation and a tradition of collegiality between bishops, as well as reverence of the Theotokos and use of the Nicene Creed. The primary theological difference between the two communions is the differing Christology. Oriental Orthodoxy rejects the Chalcedonian Definition, and instead adopts the miaphysite formula, believing that the human and divine natures of Christ are united. Historically, the early prelates of the Oriental Orthodox Churches thought that the Chalcedonian Definition implied a possible repudiation of the Trinity or a concession to Nestorianism. The break in communion between the Imperial Roman and Oriental Orthodox churches did not occur suddenly, but rather gradually over 2-3 centuries following the Council of Chalcedon. Eventually the two communions developed separate institutions, and the Oriental Orthodox did not participate in any of the later ecumenical councils. The Oriental Orthodox Churches maintain their own ancient apostolic succession. The various churches are governed by holy synods, with a primus inter pares bishop serving as primate. The primates hold titles like patriarch, catholicos, and pope. The Alexandrian Patriarchate, the Antiochian Patriarchate along with Rome, was one of the most prominent sees of the early Christian Church. Oriental Orthodoxy does not have a magisterial leader like the Roman Catholic Church, nor does the communion have a leader who can convene ecumenical synods like the Eastern Orthodox Church. Some Oriental Orthodox Churches such as the Coptic Orthodox, Ethiopian Orthodox, Eritrean Orthodox, places a heavier emphasis on Old Testament teachings than one might find in other Christian denominations, and its followers adhere to certain practices: following dietary rules that are similar to Jewish Kashrut, require that their male members undergo circumcision, and observes ritual purification. Non-Chalcedonian Christology The schism between Oriental Orthodoxy and the adherents of Chalcedonian Christianity was based on differences in Christology. The First Council of Nicaea, in 325, declared that Jesus Christ is God, that is to say, "consubstantial" with the Father. Later, the third ecumenical council, the Council of Ephesus, declared that Jesus Christ, though divine as well as human, is only one being, or person (hypostasis). Thus, the Council of Ephesus explicitly rejected Nestorianism, the Christological doctrine that Christ was two distinct persons, one divine (the Logos) and one human (Jesus),