I recently completed a series with an atheist as we had this debate: Is A Prime Mover Necessary? It was very entertaining, very enlightening and very thought provoking. My opponent was the eAtheist named Rev, and he was much more courteous, much more polite, and much more intelligent than myself. But despite that, he is wrong, a Prime Mover is necessary for the universe to exist, and I think I made that case thoroughly in our dialogue.
The links below are the fulness of our debate.