While religous stuff in sci-Fi can be interesting when done well, I'm glad Star Trek pretty much ignores it when it comes to the main crews. Not counting DS9, there was never much religious stuff when it came to the humans. I'm not an atheist, but I'm not super religious, and I prefer my sci fi crews to do interesting things, not debate or have talks about religion. It was fine in DS9 because of the way it was done, andthe sheapard in Firefly was a good character, and religion seems to be done well in B5, but I wouldn't want it to come up too often. I guess what I'm saying is that it depends on the show. I wouldn't want the Next Generation crew to take time off from exploring to have an episode involving earth religion, but I'm fine watching episodes about the prophets in DS9.
I don't think I was suggesting that the characters would debate religion. It would just be a part of who they are, it would inform their behavior. Their actions.
But then I think the blandest characters in Sci Fi can be found in TNG.