The Council removed the condemnations, which were added to the Council of Nicaea, because they didn’t fit the new terminology any more; and it did something else that was important and which was lacking in Nicaea, namely they said about the Holy Ghost: “And in the Holy Spirit, the Lord and Giver of life, Who preceedeth from the Father, Who with the Father and the Son together is worshiped and glorified.” Of course the latter phrases are more mystical and liturgical; but these abstract formulas mean more than they would mean for us, or for a logical positivist. They mean mystical power, at the same time, and therefore they can be used liturgically.
This decision ends the Trinitarian struggle. Arius and Sabellius and many of their mediating followers were excluded. The homoousios stands now against Arius in all subsequent Church history. But it was interpreted as homoiousios (as similar with God) against Sabellius.
Now in all this the negative side of the decision is clear, but its positive side, the implications for a development of the Trinitarian doctrine, are extremely difficult. I will show you the four main difficulties.
1) The Father is, on the one hand, the ground of Divinity. He is, on the other hand, a special persona, a special hypostasis. Now if you take these two points of view together, then it is possible to speak of a quaternity instead of a trinity, namely to speak of the Divine substance as the one Divine Ground, and the three persons, Father, Son and Spirit, as the manifestations of this Ground. Then we have a quaternity instead of a trinity. And there was always an inclination in this direction, and Thomas Aquinas still had to fight against it. Usually theology said: He who is the Father is at the same time the source of all Divinity, and that means, of the other manifestations also.
