 The universe? We don't know. Nobody knows. And postulating that God did it just pushes it back one more step, because you can always ask, well, if everything needs to be created, what created God? And if you say, well, God is that which does not need to be created, we could say the same thing about the universe. The universe is just simply that which does not need to be created. It always existed. Now, there is a Big Bang, so there was a start to this universe, but a lot of cosmologists think there's multiple universes,