The Oriental Orthodox Family
Oriental Orthodox Churches preserve the faith constituted in the first three ecumenical councils: The First Council of Nicaea, the First Council of Constantinople and the Council of Ephesus. These Churches are also called Old Oriental Orthodox Churches. The Oriental Orthodox Churches parted ways with the rest of Christianity in the Fifth Century.
While the Roman and Byzantine Churches came to accept Chalcedon as the Fourth Ecumenical Council (alongside the first three Ecumenical Councils), the Oriental Orthodox Church acknowledges only the first three Ecumenical Councils. Their theology closely follows the teaching of St. Cyril of Alexandria. The Oriental Orthodox rejects Nestorianism. Hence, they advocate a formula that emphasizes the unity of the Incarnation over all other considerations. The Oriental Orthodox Church also rejects the Monophysite teachings of Eutyches and teachings of Nestorius.
The Oriental Orthodox Communion
Coptic Orthodox Church of Alexandria (French Coptic Orthodox Church); Syriac Orthodox Church of Antioch and All East (Jacobite Syriac Orthodox Church of India); Armenian Apostolic Orthodox Church (Mother See of Holy Etchmiadzin, Holy See of Cilicia, Armenian Patriarchate of Constantinople, Armenian Patriarchate of Jerusalem); Indian Orthodox Malankara Church, also known as the Malankara Orthodox Church or the Orthodox Syrian Church of the East (Independent Catholic Mission, inclusive of the Brahmavar-Goan Orthodox Church); Ethiopian Orthodox Tewahedo Church; Eritrean Orthodox Tewahedo Church.