I need help to convince my boyfriend that evolution is more than just a theory.

He told me a while ago that, as he is Agnostic, he does not believe in the theory of evolution one bit. I have yet to ask him how he thinks humans came into existence, but I really need a leg up on showing him crucial points about evolution. This hasn't interfered with our relationship at all, but in the long-run it may cause problems.

EDIT: Thank you for all the advice, I showed him the video that Otakuman posted, and he pretty much accepted it. Really didn't expect it to be so easy :)