[Low spark]

Time travel can not happen, only the present exists. You can not change the past, because then the present wouldn't exist., You can't go into the future because there is no future, much like the saying "Yesterday, today was tomorrow, but it's still not tomorrow.
But for the sake of argument, lets say someone from the future traveled back in time to about 2000 years ago. Lets say that technology has advanced so far in the future that things can be altered by merely using your mind. So say this person wanted to change the world to a better place. What would be a better way than to say he was the son of God, use his technology to create "Miracles" and then be resurrected upon his death. I think that would make great book, or movie, hmm maybe they will use this idea for Terminator III.