As you've given me one more chance (cheers), I'm going with Does God exist?.
For hundreds if not thousands of years people have wondered if there was a great power, that was omnipotent, omniscient, and benevolent. Religions have been founded on this higher power, man has fought over it, and it's probably life's greatest mystery. If everyone knew there was a god, I don't really know what would change, people would probably start living generally better lives, being better people. If everyone knew there was no god, most religions could be abolished. Catholicism for example, would be based on a great lie, and would be essentially invalid. Peace could be established (obviously not all over the world, but definitely somewhere such as those who've fought between Christianity). Proof of a God (or lack of) would really change the world, and probably for the better.