structural:summarization
Conception of the Trinity

Gregory, following Basil, defined the Trinity as "one essence in three persons ", the formula adopted by the Council of Constantinople in 381. Like the other Cappadocian Fathers, he was a homoousian, and Against Eunomius affirms the truth of the consubstantiality of the trinity over Eunomius' Aristotelian belief that the Father's substance is unengendered, whereas the Son's is engendered. According to Gregory, the differences between the three persons of the Trinity reside in their differing hypostatic origin, and the triune nature of God is revealed through divine action (despite the unity of God in His action). The Son is therefore defined as begotten of the Father, the Holy Spirit as proceeding from the Father, and the Father by his role as progenitor. However, this doctrine would seem to subordinate the Son to the Father, and the Holy Spirit to the Son. Robert Jenson suggests that Gregory implies that each member of the Godhead has an individual priority: the Son has epistemological priority, the Father has ontic priority and the Spirit has metaphysical priority. Other commentators disagree: Morwenna Ludlow, for instance, argues that epistemic priority resides primarily in the Spirit in Gregory's theology.

Modern proponents of social trinitarianism often claim to have been influenced by the Cappadocians' dynamic picture of the Trinity. However, it would be fundamentally incorrect to identify Gregory as a social Trinitarian, as his theology emphasises the unity of God's will, and he clearly believes that the identities of the Trinity are the three persons, not the relations between them.