It has very little to do with his religious upbringing, in my opinon. He's associated (what he feels are) his inadequate sack skillz with his relationships ending. Sex, or rather his inability to perform "properly" seems to have sent the girls a' running and he's trying desperately (to the point of blaming you) to avoid the same with you.
You aren't really going to able to do anything about it; it really is all up to him. Be there for him, if you can, but realize that at some point (assuming things stay status quo) you're going to have make the call on whether to walk away or not.
Edit: On further review, it seems I've poorly parroted ratbastid and abaya. So, my
new advice is to read ratbastid's and abaya's posts and take them as the stone cold truth.
