Religulous

The entire film was (likely pirated) on Google video and I managed to get the chance to watch it. The video is down now, but I recommend it. It's not fantastic, but it reiterates some important arguments in an entertaining way.

This is the end of the movie:


Edit: if these sorts of movies are your thing, and you'd like to see something with a little more substance and shorter, I recommend The God Who Wasn't There. It's only an hour and has a greater tendency to be more academic about this subject.