SERGIUS I, Patriarch of CONSTANTINOPLE. - Of Syrian origin, he was consecrated on 8 April 610 and died on 9 December 638. He placed the treasures of the churches at the disposal of Emperor Heraclius to subsidize the war against the Persians, during which he governed the Empire as regent. He defended Constantinople from the siege laid by the Avars and Persians in 626.
Sergius promoted Monenergism with the aim of reconciling the Jacobite Monophysites, who were reluctant to accept the Council of Chalcedon, but fell into a grave heresy by admitting in Christ only one energy or activity. Around 621 he won Heraclius over to his doctrine, and both propagated it in Armenia, Mesopotamia, Syria, and Egypt, where in 633 Cyrus, Bishop of Phasis, one of Sergius’s first converts, was installed in the Alexandrian see. Among Sergius’s opponents were St. Sophronius, Patriarch of Jerusalem, and St. Maximus the Confessor. Sergius wrote (633) to Pope Honorius a letter lacking in candor, proposing that no one speak any longer of “monoenergism” or “dyoenergism.” Honorius, incautiously, agreed, while St. Sophronius published his synodal letter against monoenergism. An imperial edict of 634/35 confirmed the prohibition of disputes. But given the failure of this measure, Heraclius in 638 published the Ecthesis, a work by Sergius and Pyrrhus, which spoke of two natures but only one will in Christ. Sergius still had time to convene a council in Constantinople that accepted the Ecthesis. The imperial edicts regarded as Sergius’s work were condemned at the Lateran Council (649) and by the Sixth Ecumenical Council (680–81).