And interestingly enough, the main purpose of religious theory is to explain the parts of the world that we simply can't explain. Back in the good old days of Ancient Greece, almost nothing was known in the way of the natural world. So (naturally), they created gods that would explain why we have lightning, volcanoes, the sun, the moon, etc.
Now that we DO have answers for all of those things, God has become largely irrelevant to daily life. But there are still things we don't understand, and that's where God comes into play. Where did the universe come from? What happens when we die? Do we have a soul? As far as I'm concerned, these things are unknowable. Maybe they aren't, but it sure seems to be that way. So God and religion will always have their niche in the human experience, regarding these abstract questions.