The answer behind God is that he created everything in the universe and set it into motion. Before you people flame me...

"How can something come from nothing?"
Nothing came from nothing. The only thing that makes the universe real is our ability to percieve it. The only thing that makes us think it's real, anyway.

"How could God have the power to create a whole universe?"
He doesn't have the power. This universe was created by a thought. That thought is just being played out, creating more thoughts. God's power (our power) relies in our ability to think.