Really, I find that it's fun to believe in God. Or some deity.
There are always some things you can't explain, like how the very first life came onto Earth. Somebody HAD to make that one bacteria/microorganism.
Religion is simply an answer people taught themselves in the old days when life was archaic and people weren't as scientifically aware. It really served as faith and helped many good people achieve their goals. So when we prove the big bang and evolution, we're just supposed to drop all of it? I don't believe in abolishing or denying evolution like the school board in Kansas, but I really think that religion has become a custom, something that's just celebrated and accepted. It doesn't matter if it's proven wrong, you can still believe in it. It would have been such a upheaval and would have destroyed our culture if all the scientists said, "Hey, Christianity has been disproved, so STFU with the Old Testament." Just accept it. And if you don't like it, fine. More people will still practice it.
Religions don't have to agree either. If you believe that when you commit jihad you will go to heaven with lots of virgins to sleep with, that's fine. Just nobody said they were all female virgins.