Do we need to believe that Jesus was God in order to believe in his teachings?  When I was asked this question the other day, I immediately thought of the distinction the German theologian Rudolph Bultmann made between the "Jesus of history" and the "Christ of faith."  As Bultmann saw it, it does not so much matter that Jesus lived, died, and rose from the dead as it is that we learn how to appropriate the notion of resurrection into how we live our lives.  We can appreciate what Jesus did even if we do not believe that he did it.
     This dichotomy will work for a while.  Eventually, however, it will collapse under the weight of its contradictions.  If we are to take Jesus as he and his life are presented in the New Testament manuscripts, to take in the totality of what he said and did, we can draw no other conclusion than that he was God and he lived, died, and rose again.  And we cannot fully appreciate the latter without fully accepting the former.  As C. S. Lewis observed long ago, Jesus didn't give us a choice about who we thought he was.  As he wrote,   

"I am trying here to prevent anyone saying the really foolish thing that people often say about Him: I’m ready to accept Jesus as a great moral teacher, but I don’t accept his claim to be God. That is the one thing we must not say. A man who was merely a man and said the sort of things Jesus said would not be a great moral teacher. He would either be a lunatic — on the level with the man who says he is a poached egg — or else he would be the Devil of Hell. You must make your choice. Either this man was, and is, the Son of God, or else a madman or something worse. You can shut him up for a fool, you can spit at him and kill him as a demon or you can fall at his feet and call him Lord and God, but let us not come with any patronizing nonsense about his being a great human teacher. He has not left that open to us. He did not intend to.”

     The Jesus of history must be the "Christ of faith."