Evolution is a diversion, nothing more.
As I just said to dyana, you can have evolution, we will grant you it occurred for the sake of getting on with it. The only question of any importance is this: Do not insult us by saying evolution could have occurred without God! That is when the lies really start emerging. Lies that send people on their way to an oblivious life without purpose or concern.
(As to my evidence for God, I will gladly post my challenge to you and your pals when time allows.)
Given that we're in the Evolution Vs. Creationism subforum and the title of this thread is regarding what prevents creationists from accepting evolution I'd hardly call it a diversion, I'd call it the topic.
That said, I agree whether evolution happened or not doesn't answer the question of whether or not God exists. You have four possibilities here:
God exists and evolution isn't true.
God doesn't exist and evolution isn't true.
God exists and evolution is true.
God doesn't exist and evolution is true.
In the first two, there must be some other physical cause behind our existence regardless of whether God exists or not.
In the last two, evolution is how we got here. If God exists then evolution (or really, the laws of physics in general) would simply be the method God used for our creation.
So in terms of "Does God exist?" evolution is irrelevant. It's only important in that context when dealing with religions that have a specific belief as to the methods God used in creating us, one that contradicts evolution and one that is taken to be literal.
Regarding the existence of God you'd be looking at philosophical arguments (cosmological, teleological etc). You'd be better of making a new thread for that though.