How could you not believe in a God? Without Him, morals wouldn't exist!
Argument from final consequences: that the consequence of God's nonexistence is unpleasant doesn't make his existence any likelier.
False premise: morals still exist in the abscence of God.
Give me a second and I'll post a new fallacy, but I didn't want to be scooped.
Edit: Wikipedia calls the first fallacy "appeal to consequences, also known as argumentum ad consequentiam". But they're called arguments from final consequences on the SGU logical fallacy page, so I figure I'm okay.