To say that God does not exist is to say that out of all the things that do exist, God is not among them. But who can honestly make such a claim? To honestly make that claim a person must have complete and exhaustive knowledge of everything that does exist. And the only person who can honestly make that kind of claim is God—the very person the atheist is trying to deny! 

– Doug Powell (from the Holman QuickSource Guide to Christian Apologetics, pp. 98, 100)