Third Council of Constantinople
The Third Council of Constantinople, counted as the Sixth Ecumenical Council by the Eastern Orthodox and Catholic Churches, as well as by certain other Western Churches, met in 680–681 and condemned monoenergism and monothelitism as heretical and defined Jesus Christ as having two energies and two wills.
Miniature 45 from the Constantine Manasses Chronicle, 14 century: Sixth Ecumenical Council
The Eastern Orthodox Church, officially the Orthodox Catholic Church, and also called the Greek Orthodox Church or simply the Orthodox Church, is the second-largest Christian church, with approximately 230 million baptised members. It operates as a communion of autocephalous churches, each governed by its bishops via local synods. The church has no central doctrinal or governmental authority analogous to the head of the Catholic Church. Nevertheless, the Ecumenical Patriarch of Constantinople is recognised by them as primus inter pares, a title formerly given to the patriarch of Rome. As one of the oldest surviving religious institutions in the world, the Eastern Orthodox Church has played an especially prominent role in the history and culture of Eastern and Southeastern Europe.
Saint George's Cathedral, Istanbul, Turkey
Christ Pantocrator, sixth century, Saint Catherine's Monastery, Sinai; the oldest known icon of Christ, in one of the oldest monasteries in the world.
Emperor Constantine presents a representation of the city of Constantinople as tribute to an enthroned Mary and baby Jesus in this church mosaic (Hagia Sophia, c. 1000).
An icon of Saint John the Baptist, 14th century, North Macedonia