Councils and the Deity of Christ
Frédéric Lenoir, Comment Jésus est devenu Dieu:
[Constantine] soon realized, however, that Christian divisions over the nature of Jesus were undermining his project. It was imperative for Christ's followers to agree among themselves on this crucial issue. It was therefore for eminently political reasons that he convened a council in Nicaea in 325, bringing together all the Christian religious authorities scattered across his vast empire and even beyond. He urged them to agree on the essential point that had divided them for two centuries: who was Jesus? A man chosen by God, perhaps even elevated to divine rank by the Father, or God himself made man?
It would take more than another century of terrible disputes and polemics, three new councils, and the same relentless determination of Constantine's successors to force Christian theologians to agree, before a consensus was finally reached by a large majority, establishing the key fundamental Christian dogma: Trinitarian theology. God is both one and three: Father, Son and Spirit. The Son (or Logos) has a dual nature, divine and human, Jesus being the human incarnation of the divine Logos. Jesus is therefore considered True God and True Man, begotten and not created, of the same substance (ousia) as the Father. This complex theological formulation became the basis of the Christian faith, and remains so to this day, irrespective of the Church: Catholic, Orthodox, or Protestant.1
Lenoir is somewhat dishonest here. He speaks of “three new councils” and “more than a century of terrible disputes and polemics” between 325 and 451, when he knows full well that the question he is talking about was in fact settled at Nicaea in 325. The formula he cites as the conclusion to all these debates is none other than the Nicene Creed:
We believe in one Lord, Jesus Christ, the only Son of God, eternally begotten of the Father, God from God, Light from Light, true God from true God, begotten, not made, consubstantial to the father. Through him all things were made. For us and for our salvation he came down from heaven: by the power of the Holy Spirit he became incarnate from the Virgin Mary, and was made man.
It was at Nicaea that the debate took place over the full deity of Christ, because the priest Arius taught that the Son was a lesser god, created by the Father. His perspective was firmly rejected at Nicaea, and the formula of faith adopted by the council insists that Jesus is “true God from true God,” “begotten, not created,” and “consubstantial with the Father.” Only two of the 200-250 bishops present rejected this formulation.
Subsequent debates and the ensuing councils (Constantinople 381, Ephesus 431, Chalcedon 451) had to do with the exact relationship between Christ's divinity and humanity, but there was no longer any question of whether Jesus was God, only how he could be God and man at the same time.
Lenoir, Frédéric. Comment Jésus est devenu Dieu. Paris: Fayard, 2010, p. 12-13.