To which Rip would prank, "Who is this Jesus fellow? Was he someone important?"

I think Dini and crew summed it up best in Batman Beyond:
Bruce: These people believe that anything they can't explain is magic.
Terry: And naturally you don't believe in that kind of thing.
Bruce: Of course I do. I've seen it all. Demons, witchboys, immortals, zombies...

Bruce takes a very secular few of all this though. Everything can be quantified, so it's less "outside science" and more "another set of rules." But yeah, faith for Bruce is difficult. He relies so much on himself and what he's built, it's hard for him to have belief in something greater than himself.