The liturgical traditions of the East derive ultimately from the forms of worship used in Antioch and Alexandria. As with all ancient Christian liturgies, the Service of the Word led into the sacramental offering of the Eucharist. The Eastern traditions comprise the East and West Syrian, the Byzantine (including the Greek and Russian Orthodox), the Armenian, and the Coptic/Ethiopian.
Since Apollinaris’ doctrine marred the perfection of his humanity, it was condemned at the Council of Constantinople in 381. This same Council asserted the divinity of the Holy Spirit. From that time the Athanasian doctrine of the Trinity has held the orthodox position in Christianity.
The schools, especially the one in Alexandria, preserved early writings and produced important scholars who impacted the church for centuries.
Alexander of Alexandria (d. 328) defended orthodoxy against the heresy of Arianism.