You all seem to be looking at this a little backwards. There must be an uncaused cause in order to have any other causes. Everything that begins, needs a cause. So in order to have anything at all, you need something that hasn't begun, a foundation for all other causes. That first cause is what we call God. It isn't the other way around. It is not that we have God and we have the first cause and we just equate them. It is that we have the first cause and that is God. It is a subtle but important difference.

@hairy - the reason the universe is not exempt from causality is that it had a beginning, and anything that begins to exist, has a cause. If the universe did not have a beginning, it would not have required a cause. (And by universe I don't just mean the current arrangement of matter - but matter/energy itself).