"The Orthodox Church in the Byzantine Empire" describes the role of the medieval Orthodox Church in the Byzantine Empire (c.600-c.1453). As an integral part of its policy it was (as in western Christianity) closely linked with many aspects of everyday life both official and otherwise. It was a formative period for Orthodoxy.

It had to face doctrinal problems and heresies; at the same time it experienced the continuity and deepening of its liturgical life. While holding fast to the traditions of the fathers and the councils, it saw certain developments in doctrine and liturgy as also in administration.