Constantine I of Constantinople

Saint Constantine I was Ecumenical Patriarch of Constantinople from 675 to 677, successor of John V. The Church remembers him as a devout shepherd and a defender of right belief against Monothelitism. His feast is kept on 29 July.

Before becoming patriarch he was a deacon and skeuophylax, keeper of the Church's treasury, at the cathedral of Hagia Sophia. He was raised to the patriarchal throne in 674 or 675. His ministry fell in the time of Emperor Constantine IV. In that period the imperial Typos of 647 or 648 was still in force, forbidding dispute about one or two wills and operations in Christ. The council's decision came only after the patriarch's death. According to the chronography of Patriarch Nikephoros, he governed for one year, eleven months and seven days, and church sources reckon his death on 9 August 677.

At the thirteenth session of the Sixth Ecumenical Council in 681, the letter he had sent after his election to Patriarch Macarius of Antioch was examined. The council found nothing contrary to its own faith in it and left his name in the diptychs. In this his judgment after death differed from the condemnation of Sergius, Pyrrhus, Paul II and Peter. His memory is entered in the Synaxarion of Constantinople, compiled at the end of the tenth century, under 9 August. After him the throne was held by Theodore I.