The idea of an Ecumenical Council is a retrospective recognition of something which when it happened was not viewed in that way. Local churches often called councils, and Nicaea in 325 was in many sense just another such. It derived its importance from the fact that it was called by the Emperor. But although it promulgated the first version of that Creed whose name we repeat every Sunday, many did not accept it. The continuing popularity of Arianism, plus the teachings of Apollinaris, required attention, as did the arguments about the precise relationship of the Holy Spirit to the Father and the Son.
It is unclear whether Pope Damasus I even knew that the Empror Theodosius summoned bishops to a meeting in Constantinople in May 381; it is clear that he was not asked to send, and therefore did not send, a representative, and it appears likely that he did not even know the results of it. Although it is common to say that it was the Council which modifed the Creed of Nicaea, it would be truer to say that it ratified a variation that was already in use.
The Nicæno-Constantinopolitan Creed, besides some minor changes in the first two articles, added all the clauses after ‘Holy Ghost,’ but omits the anathemata present in the original version of 325. It gives the text as now received in the Eastern Church. There is no authentic evidence of an ecumenical recognition of this enlarged Creed till the Council at Chalcedon, 451, where it was read by Aëtius (a deacon of Constantinople) as the ‘Creed of the 150 fathers,’ and accepted as orthodox, together with the old Nicene Creed, or the ‘Creed of the 318 fathers.’ But the additional clauses existed in 374, seven years before the Constantinopolitan Council, in the two creeds of Epiphanius, a native of Palestine, and most of them as early as 350, in the creed of Cyril of Jerusalem.
The Creed omitted the explicit denunciations of Arianism and preferred, instead to assert the identity of Jesus with the Father, and to say more about the role of the Holy Spirit, who proceeded from the Father (no ‘and the Son’, note). It also reaffirmed the humanity of Christ by bringing into the Creed the Virgin Mary. This, as we saw in the series of posts about St Cyril of Alexandria and the Council of Ephesus, was a necessary part of explaining Christ’s genuine humanity.
Thus, by 381, the Church had effectively thought its collective way to the notion of the Trinity as enunciated by the Cappadocian Fathers. Jesus was definitively defined as being of one substance with the Father, as preexisting with Him from the beginning, and the Holy Spirit had been defined as an equal member of the Trinity. So much for those who suppose that the nature of Christ and of Christian belief proceeds naturally from one’s own unaided understanding.
Theodore of Mopsuestia and Arius and Appolinarus were not bad men, they were learned men well-versed in Scripture, but they insisted on their view, and when pushed, the majority of bishops in council could not find them to be correct. But the question of the nature of the Incarnation was not settled. Yes, Christ was fully God and fully human. It would take another Council at Ephesus, and a further one at Chalcedon in 451, to tease out these matters further, but with this post, we come to the end of this series tracing the development of Christological thought from the Apostles to Ephesus. There is one more historical post to come, on the Holy Spirit, before I move on to sum up.