In the early centuries of the Church the Fathers used specific terms when explaining Trinitarian theology and Christology:
Person:
- Prosopon (Greek)
- Parsopa/Farsofa (Aramaic)
Individual Existence/Subsistence:
- Hypostasis (Greek)
- Qnoma (Aramaic)
Substance/Essence:
- Ousia (Greek)
- Ousia (Aramaic)
Nature:
- Physis (Greek)
- Kyana (Aramaic)
Saint Cyril of Alexandria taught that the hypostatic union was a union out of two hypostasis, a divine hypostasis and a human hypostasis to create one composite hypostasis. The Oriental Orthodox Church confesses that Christ was one composite hypostasis out of two, a divine and human hypostasis. The Chalcedonian churches confess that Christ only had a simple divine hypostasis with human properties, while also having a human ousia. The Assyrian Church of the East confesses that Christ has one Prospon (person), two hypostasis (qnoma) and two natures (kyana).