As expressed in John 1 and Hebrews 1, Jesus Christ is the ultimate and definitive revelation of God because he himself is the Word to which the prophets and apostles, like John the Baptist, were merely witnesses. Thus, when it comes to interpreting Scripture and formulating theology, we cannot start with an approach that we have developed or adopted from sources or philosophies external to this witness. Rather we must allow the form of our interpretive and theological method (and not just the material content!) to be shaped and determined by Christ who must be the Alpha and the Omega of all our thought and speech about God.
I would argue that this approach to Scripture and theology is necessitated by what we read in John 1:14, 18:
And the Word became flesh and dwelt among us, and we have seen his glory, glory as of the only Son from the Father, full of grace and truth…. No one has ever seen God; the only God, who is at the Father’s side, he has made him known.
In this passage, the apostle John makes clear that the form of God’s definitive self-revelation is inextricably bound up with its content, because “the Word became flesh” was both the message and the medium. Jesus Christ, the Word enfleshed, did not simply reveal God; he himself was also the God whom he revealed. It would be impossible, therefore, to separate what Christ revealed from the way in which he revealed it, for both were bound up with his incarnate person. Additionally, we must remember that Jesus Christ was not merely the Word of God to humanity, but — precisely as that Word become flesh — he was also humanity receiving and responding to God in perfect faith and obedience. It is in Christ alone that we discover not only the perfect revelation of God, but also the perfect apprehension of that revelation by a human mind, heart, and soul.
As a result, those who seek to apprehend this revelation (interpretation) and then to say what needs to be said on its basis (theology) can do so faithfully only insofar as they refuse to separate what God has joined together: both the message and the means of making it known. Only a methodology that respects this union of form and content by adapting itself to the nature of Jesus Christ will yield the true knowledge of God that both reveals and reconciles. Is this not what Paul meant when he stressed the necessity of taking every thought captive to Christ (2 Cor. 10:5)?
To conclude, here is an eloquent statement of this by “Christo-logian” par excellence Thomas F. Torrance [Theology in Reconstruction (Eugene: Wipf & Stock, 1996), pp.129-130]:
Christian knowledge of God arises out of the self-revelation of God in and through Jesus Christ, for in him the Word of God has become man in the midst of man’s estrangement from God, committing himself to human understanding and creating communion between man and God. Biblical and dogmatic theology is the careful unfolding and orderly articulation of this knowledge within the sphere of communion with God, i.e. the sphere of reconciliation into which we are drawn by the activity of his Word, and of the obedience of faith in which all our thinking and speaking is brought into conformity to the self-communication of his Word. The way which God has taken in Jesus Christ to reveal himself and to reconcile us to himself is the way which we have to make our own in all true understanding and thinking and speaking of him.
Theology, therefore, involves a knowledge which is determined and controlled in its content by what is given in Jesus Christ, and operates with a mode of rational activity which corresponds to the nature of the object of this knowledge is Jesus Christ. It is the incarnation of the Word which proscribes to dogmatic theology both its matter and its method, so that whether in its activity as a whole or in the formulation of a doctrine in any part, it is the Christological pattern that will be made to appear. That does not mean that all theology can be reduced to Christology, but because there is only one Mediator between God and man, the Man Christ Jesus, in the orderly presentation of the doctrines of the Christian faith, every doctrine will be expressed in its inner coherence with Christology at its centre, and in its correspondence to the objective reality of God’s revelation in Jesus Christ who is true God and true Man…
We cannot divine between the so-called form and content, between the human word of revelation and revelation itself, any more than we can divide asunder the human and the divine natures which are united in the one Person of Jesus Christ. The inconfuse, immutabiliter, indivise, inseparabiliter of Chalcedonian Christology apply equally to our understanding of revelation. Revelation is not only act from the side of God but also from the side of man, in the form of the Humanity of Christ which is of the very substance of revelation. The divine form and the human form of revelation must neither be confounded nor be separated. The incarnation means that now revelation is determined and shaped by the Humanity of Christ, that we know of no revelation of the Word of God except that which is given through Christ and in the form of Christ. Jesus Christ is the Truth, Truth as God is Truth, and that same Truth in the form of Man, Truth answering itself, Truth assuming its own true form from the side of man and from within man.