Personally, I reckon that in order for everything to happen, the past must act like the future, if you catch my drift? How do we know that the past isn't as infinite as the future? Like a rewinding movie that never ends. There could have been a God that created God. And one before that God, untill infinite. It's a possibily. If you aren't religeous you could still put the same theory to a different test. It could be infinite that something caused the big bang and that something created that etc. My personal belief.
Check out my video blog at:
http://www.youtube.com/watch?v=NxVKEWusSAk