There are some very simple reasons why we have come to put Christ at the center of our theology - He's the one who came to us in the flesh, looking and living and loving like us and He's the one who seems to have done the most for us. I mean, that whole salvation/redemption thing is pretty cool, especially if you happen to be a fallen, broken, sinful human.
But to buy into these ideas and to give them the primacy that we have requires wearing some pretty hefty theological blinders. It's our self-centered/human-centered interpretations that have led us here, not the objective testimony of the Scriptures.
Take the first claim: Jesus is central because He's the one who walks with us. This is true - Jesus does walk with us. He lives with us. He loves with us. He's in this world just like we are, trying to wind His way through it.
Go back to the Old Testament for a bit, though. Start at the beginning. In the beginning, there was a Garden, and God walked in it with His people. Adam. Eve. God, the Creator. (God, the Father.) Enoch walked with God. Abraham walked with God. Moses met with God on the mountain, and not just once. God came to Elijah, and we have a recorded conversation between God and Jonah. God, the Father, is very present throughout the Old Testament. He may not (or maybe He did) have had a physical body in the same way that Christ embodied the flesh, but He walked with His people nonetheless.
And after Jesus's ascension, the Holy Spirit came down upon the people. The rest of the New Testament, although it continues to recount the Jesus story in the same way that the Old Testament continues to look forward to it, tells of the Holy Spirit's very real presence among the people. The Holy Spirit provides interpretation and inspiration. The Holy Spirit brings the gift of language. The Holy Spirit is counselor, comforter, just as Jesus promised He would be. The Holy Spirit, who may not (or maybe He does) have a physical body in the same way that Christ embodied the flesh, is present among God's people in the same way that God, the Father and Christ, the Son have been.
So it takes quite a leap to say that Christ is central because He is the one who walked among us; the whole of the Trinity walks among us. We just happen to recognize Christ's flesh a bit more easily.
Or take the second claim: Jesus is central because He's the one who did the most for us. He came, lived, died, and was raised again that we might have eternal life with Him. He's the one who made atonement for our sins. He's the one who made righteousness possible.
But God, the Father, is the one who made this whole thing possible in the first place. In the beginning, there was nothing. Then, God, the Father, made this entire cosmosphere in order to put His special creation - human beings - into it. God, the Father, formed Adam from the dust, bent over, and breathed the breath of life into Him. God, the Father, led His people from captivity in Egypt through the barren, broken wilderness in a column of fire and smoke.
And let's not forget that God, the Father, sent His Son in the first place, and it was God, the Father, who accepted His sacrifice.
The Holy Spirit is the one who gives us the ability to understand any of this. He's the one who lets us understand what Christ truly means. He's the one who puts it all in perspective and lets us live in truth even in this place of shadows. The Holy Spirit came to keep alive the Spirit of Jesus among the people. If it were not for the work of the Holy Spirit, the story of Jesus would be long gone by now. Nobody would be remembering it because nobody would be living it; it would be a historical event, over and done with. But by the Spirit, we live the grace of God through Jesus Christ - and only by the Spirit - and thus keep the story alive. Without the Spirit, not one word of the Bible would have been preserved for us, but that wouldn't have mattered because without the Spirit, we could never have understood it anyway.
So tell me again how Christ is the only member of the Godhead who ever did anything super-important for you.... That's just not the testimony of the Trinity. We need all three persons, just as much as we need Christ, for it is through the Three-In-One that we have being, atonement, and understanding. It takes all three.
Again, I'm not saying that what Christ accomplished or what Christ did - His life, His love, His sacrifice - was not important; I'm saying that we cannot let the Son obscure for us the Father or the Spirit. We cannot let our theology rest in some false centrality of Christ when the testimony of the Scriptures, and of Christ Himself, is that there is a Triune God who cares for us. (That's a bit more simplistic than I'd like to leave it, but I'm building on something here, so it will have to do.)
We'll look more at what Jesus had to say about this tomorrow.