5th–8th centuries

The Trinity in Eastern disputes after Chalcedon: the Trisagion, "one of the Trinity suffered" and the synthesis of John of Damascus

Pelikan shows that the christological disputes after Chalcedon posed the problem of the Trinity in a new way. When some Monophysites identified hypostasis with nature, their opponents pointed out that this led to three ousiai and tritheism. In Antioch the words "crucified for us" were added to the Trisagion, and the question arose whether "one of the Trinity" had suffered; the dispute over whether the hymn is addressed to the Trinity or to Christ lasted for centuries. In the 7th–8th centuries opponents called Monothelitism a "new tritheism": will and action belong to the nature, which is one for the Three. In the East the doctrine was definitively formulated by John of Damascus: one substance and three Hypostases, one in everything except the mode of existence, interpenetrating without confusion.