Just be honest with him, like, send him roughly the info that you wrote in this post.
I personally wouldn't date someone with such differing religious beliefs, but I also know people who've made this work... although expectations are something to manage for sure.
Anyways, the guy seems a bit confused here, which is probably not too surprising since it seems your feelings for him are maybe unclear, even for you?
If you don't know what you want yourself, there's little chance that the other person does either.