Hey, live and let live.
Don't worry too much on the core values of friends, if you guys get along, great, don't let petty things like religion or non-religion get in the way of a good friendship. let him know that too.
Hope it works out!
Jonathan said it so wonderfully. Live and let live.
I think you're doing the right thing. Be nice, hang-out if you want, but not totally trust him until you are sure he is sincere.
If you can get past it, it's all the better. Don't trust him too much (is he trying to get you saved?) and don't talk about anything controversial (don't want to get into fistfights!).
Keep your friends close and your enemies closer. Either way, keep at least one eye on him.
if you were kicked in the nuts once maybe
2x? don't let there be a third is my motto
cauterize the beef!
my best friend in junior high was my best enemy during school days