It's why it's important to nail down the definition of "universe" right at the start, so the theist can't play Dolphinetics with the word. Is it "the set of everything from the Big Bang onwards", "the set of everything that can possibly exist" or something else? Because they're not all interchangeable.
At the age of five, Skagra decided emphatically that God did not exist. This revelation tends to make most people in the universe who have it react in one of two ways - with relief or with despair. Only Skagra responded to it by thinking, 'Wait a second. That means there's a situation vacant.'