Behold the Man by Michael Moorcock
This novella won the 1967 Nebula Award.
Karl Glogauer travels back in time two thousand years, meets John the Baptist, and then seeks Jesus Christ himself. This is a very intense read. At first I thought Ok, a time travel novel. Then as you see how Glogauer interweaves himself in this timeless story I became amazed by it. It is really hard to discribe my thoughts and emotions while reading this. Wow!