The Subject of All Theology
Jesus Christ is the focus and subject of all theology. He is not only the author and perfector of our faith and salvation (Heb 12:2), but is the the author and perfector of all things excellent, for in Him all things are consummated (Col 1:16-20). All theology is, therefore, Christology, for what we can, and do, know about God is summed up in the person of Jesus Christ. All light concerning God is refracted only through the Christ who has worked and revealed HImself through redemptive history. This means that all attempts to try to understand God redemptively in any sense that is different than Christ is futile, for apart from Jesus Christ, He is unknowable. While reason and creation may give us an idea of God and His greatness, only in the revelation of Christ can we come to know Him. While in Romans 1:18, 21 it says that the unregenerate "know" God as well, but the text makes clear that they only know Him as an enemy. Only through Christ do we know Him as a friend.
Calvin once said, "...it is obvious, that in seeking God, the most direct path and the fittest method is, not to attempt with presumptuous curiosity to pry into his essence, which is rather to be adored than minutely discussed, but to contemplate him in his works, by which he draws near, becomes familiar, and in a manner communicates himself to us."(Institutes Book 1, Chapter 5, section 9) In other words, we should only attempt to know God as He has revealed Himself to us. Other attempts are vain speculation.
So why study theology? Because theology is an interpretation of God as He revealed Himself, a revelation which was fulfilled in the gospel-event of Christ which took place in space-time history. The gospel is a narrative of the story of Jesus as Godâ€™s historical act to which all revelation pointed. It narrates the history of Jesus as the history of redemption that culminates in Christ's physical death and resurrection. The gospel defines the God who has revealed Himself in Christ Jesus, the eternal Son of God. Incarnate to redeem His covenant people, He was executed on a cross, and was raised to life: this is the Christian definition of God which was fulfilled in His decisive act. "All the wisdom of believers", said Calvin, "is comprehended in the cross of Christ."
So it is an extremely urgent task in our era of religious chaos, that we use the word â€œGodâ€ only as describing the event that culminated in the history of Jesus Christ, God made flesh for His glory and our redemption. When we speak of the benefits of truths such as the doctrines of grace, they should never be spoken of as divorced from the Benefactor. And when we speak of God's various perfections, we do not simply speak in abstractions, but of a historic person who walked among us. God's love, glory, wrath, holiness are all seen to perfectly unite in the person of Jesus.