Oh honey. Why are you bothering with this person? Just let the religious nuts drift into the periphery of your social life. There is no way around that kind of crazy.
Mmm, I'm optimistic about locking them in a room for a marathon de-programming session. Just write down all their arguments so you can keep track of the ones you've refuted, and keep going until they've run out.
Or you can find some non-psycho friends, either way works. But there's something to be said for destroying the bogus faith of a self-righteous asshole.
While that does sound fun, it also sounds futile. If religious people were willing to give up on arguments that have been refuted, there would likely be no more religious people. No, they prefer to just ignore you and go on repeating the same arguments over and over, eyes squeezed shut and fingers in their ears as if to say "LALALALALA I CAN'T HEAR YOU!!!"
Or you can find some non-psycho friends, either way works. But there's something to be said for destroying the bogus faith of a self-righteous asshole.