An Explication of the Doctrine of the Trinity is made in Four Positions.
1. That in God there is One, altogether Simple and Singular, Essence. This was proven in Chapter IV, § 23, 24, which is here to be observed against the Tritheists and Triformiansespecially. The Tritheism of John Philoponuswas treated in Chapter IV, § 23, and it was seen that he did indeed blush to assert Three Deities or Three Gods, and held that the individual Persons possessed μίαν καὶ ὁμοούσιον θεότητα, one consubstantial divine nature; but that he nevertheless meant that the Three Hypostases in the Deity are altogether three φύσεις, Natures or Substances, also. From these Tritheistic followers of John Philoponus differ the Triformians, 1. both with respect to time, since the Triformians are referred to the end of the fourth, or beginning of the fifth, Century; but the Tritheists to the end of the sixth, and beginning of the seventh, Century. 2. And with respect to doctrine, since the Tritheists were asserting the Three Persons to be Three φύσεις/natures: but the Triformians were establishing One divine Essence in three Persons, but not a whole Essence; while they suppsed the individual Persons to possess a part of that, from which the whole coalesces. In any event, AUGUSTINE tells it in this way, de Hæresibus, chapter LXXIV: “It is a different position, that asserts a Triform God, in such a way that the Father is a certain part of it, the Son a certain part, the Holy Spirit a certain part, that is, inasmuch as they are parts of the one God, which make up that Trinity, as if God were made a complete whole from those three parts, and neither the Father, nor the Son, nor the Holy Spirit, were Perfect in Himself.” Concerning the more recent Tritheists and the rest not admitting a perfectly Simple Unity of the Essence of God, it was treated in ChapterIV, § 23.
John Philoponus (c. 490-c. 570) was an Alexandrian philologist, philosopher, and Christian theologian.