I'm amused by finding ways to piss off the religious guy.
Why did you want to piss off a religious guy?
I'm so tired of him telling me how great God is. It's really annoying me.
You should tell him that he's bother you and you don't want to talk about religion or God. You don't have to piss him off, just state clearly how you feel and that you don't want to talk about those subjects.
He won't understand unless I yell at him.
People feel very passionate about religion. Just make it clear that you don't want to hear about his religious beliefs and be gentle about it. If you show him kindness, he's more likely to respect your wishes.