Once a believer has fully grasped the decisive significance of homoousion, there can be no returning to a more “biblical” or more “historical” Jesus; for the only Jesus that was and is is the incarnate Son eternally begotten from the substance of the Father. The homoousion represents the secret of our Lord’s personhood, a secret both intimated and implied in the New Testament, yet perhaps not so unambiguously asserted as to eliminate the possibility of misunderstanding. In the theological reflections of the first four centuries, we see theologians wrestling with the mystery of Christ and proposing various construals of his relationship with God. Some proposals may have initially appeared plausible yet were eventually deemed inadequate to the apostolic revelation. The secret kept eluding the conceptual apprehension of the Church.
I do not mean to suggest that in these early centuries Christians did not know Jesus as fully divine. We know many truths that we cannot adequately express in words. Long before the clarity bestowed by the homoousion, Christians worshipped Jesus as the Son of the Father and offered to him the adoration and prayer reserved for the One God (see David Yeago, “The New Testament and the Nicene Dogma“). This is a knowing of Christ that only the Holy Spirit can give. As the Apostle taught, “No one can say, ‘Jesus is Lord,’ except by the Holy Spirit” (1 Cor 12:3).
T. F. Torrance has likened the early developments in trinitarian doctrine to putting together the pieces of a jigsaw puzzle. Initially the pieces are spread upon a table, and we cannot see how they fit together. We try numerous combinations, but more often than not they do not quite fit. We may even try to force pieces together but always unsuccessfully (unless, of course, we cheat and resort to the scissors method). But after hours and hours of work, more and more pieces come together and eventually we begin to see the pattern; and once the last piece is put in place, we know the picture. From that point on we can never pretend that we have not grasped how all the units are properly joined nor what image they intend.
In the Nicene formulation of the homoousion something absolutely fundamental took place in the mind of the early Church. It was a decisive step in deeper understanding of the Gospel, taken in the continuity of the apostolic tradition, upon which the Church, in obedience to God’s saving revelation in Jesus Christ, could not go back. It was an irreversible event in the history of Christian theology. The significance of what happened may be indicated by reference to what we do with a jig-saw puzzle. We assemble the scattered pieces together, fitting them appropriately to each other until the pattern they conjointly make comes to view. If we then break it all up and throw the pieces back into disorder, we may have little difficulty in fitting them all together again, but it will be impossible for us to do that without recalling the picture we reached the first time. Something irreversible would have taken place in our mind and memory, which could not but influence all subsequent attempts to recover the coherent pattern made by the different pieces.
An ineraseable event of that kind happened in the mind and memory of the Church at the Council of Nicaea in 325 A.D. It was a turning-point of far-reaching significance, with conceptual irreversibility. When the conception of the oneness in being between the incarnate Son and the Father was formed and given explicit expression in the clause όμοούσιοϛ τω Πάτρι, a giant step forward was taken in grasping the inner ontological coherence of the Gospel as it had been mediated through the apostolic Scriptures. Once that insight had been reached, the Church could not go back upon it, because the evangelical substance of the faith, with its distinctively Christian doctrine of God, had been secured in its mind and understanding in a permanent way. (The Trinitarian Faith, pp. 144-145)
In this way the Nicene homoousion entered into the consciousness of the Church and became dogma. Not only does the homoousion now function as the fundamental grammatical rule for homiletical and theological discourse, but it also functions as hermeneutical rule for our exegesis of the Scriptures. Without apology, we read the Old and New Testaments within our knowledge of the identity in being between Christ Jesus and God the Father. The homoousion is the key that opens the Bible and brings all the disparate and confusing elements into a unified story. As Christians have insisted since Pascha, every page, every verse, witnesses to the crucified and risen Son. After Nicaea this deep reading of the Bible becomes even more intensified and powerful: the story of Jesus is nothing less than the story of the eternal God himself. This is the secret of the homoousion.