Quote Originally Posted by acidtrip
Motion
In the universe, there are objects in motion, each object in motion must have been caused to move by something else. Because nothing is infinite, there must have been a first motion or "prime mover" which was unmoved, this prime mover began all movement without bieng moved, Aquinas stated that the "prime mover" must have been God.

Causes
Nothing can be the cause of it's self, as it would have to 'exist' before bieng caused. This of course is impossible, so like with motion there must have been a first "un caused" cause, that started a chain of causes. This is God.
These are really two different forms of the same argument. And they're easily refuted, since, as you said yourself, everything requires a cause and nothing can be the cause of itself. Therefore, if there is a God, what caused God if God cannot possibly be the cause of himself? And if we're willing to allow a single exception to such a rule, why postulate the existence of a God? Why not simplify things and just say that the universe was the cause of itself, rather than saying some big invisible undetectable creature was the cause of itself, which then started the whole universe thing?

And why could the chain of causation not extend back forever? I know it's hard for us humans to imagine, since we only ever experience finite amounts of time, but there's no scientific reason it couldn't be the case.

Contingency
There must have been a time when nothing existed,
Says who?
the cause of the universe would have to be outside of the universe and must have always existed. There muse have been something to cause the universe to exist, this is God.

Of course, this can also be applied to the big bang. So you could say

God = the Big Bang.
But that's misleading. Nobody prays to the Big Bang, nobody worships the Big Bang, and there is objective data to support the idea that there was a Big Bang. Plus, the Big Bang is no longer around. So why call it God?