The Sixth Ecumenical Council
The defining event of George's patriarchate was the Third Council of Constantinople, reckoned by the Eastern Orthodox and Catholic Churches as the Sixth Ecumenical Council. Emperor Constantine IV summoned the patriarch and the bishops of his jurisdiction to a council to resolve the long-running dispute over whether Christ possessed one will or two. George took part in person and is recorded as president of the council, alongside the participation of the Patriarch of Antioch.
The council opened on 7 November 680 in the imperial palace, the emperor presiding over its early sessions, and closed at its eighteenth session on 16 September 681, by which point its membership had grown to roughly 151 bishops. It condemned Monothelitism and Monoenergism as heretical and defined that in Christ there are two natural wills and two natural energies, the human will being in harmony with and subject to the divine will.