Making it clear: I'm an atheist. And this movie offends me intellectually. The premise of the movie seems to be that religion is absurd. But instead of taking down the most powerful (in terms of influence) of religions (Christianity, Judaism, Islam and also Buddhism, Hinduism, at least), they pick some fanatics and eccentrics and make fun of them. What is that? Does that represent religion at all? That is ridiculous.
Saw this at the cinema twice upon its release; didn't see it for two years; took another look. Still funny. Ditto its DVD commentary. People whine about its "manipulative editing". Those same people have no problem with the "editing" of ancient religious texts by modern theologians. Have you been spoken at like a retard for not believing in God? (Me, many times) Enjoy this film! It's about time atheists had some say.
Anyone want to go on a vacation to the Holy Land with me? Maher's documentary seems to a part of that mid 2000s wave of atheism that spawned Dawkin's The God Delusion and such personalities as The Amazing Atheist. It isn't a great documentary, but it's a lot of fun, and Maher is always entertaining. The ending with depictions of nuclear holocaust came out of nowhere. For some reason I'm reminded of Bunuel.
Criticizing it for the format of its argument is missing the point. If you're looking for a serious debate, look for Dawkins, Sagan, etc instead. Maher being a comedian doesn't necessarily means he's 'acting' as pointed out below, but the film/documentary is comedic, low-fi and obviously aimed at ridiculing the absurd beliefs held by different groups. Just a lighter way to tackle the subject, but just as necessary.
Despite the fact I pretty much agree with Maher's position, this is a terrible documentary. It is very easy to mock religion (often it mocks itself without realising) so to base a whole documentary on it automatically makes it impotent of any value. If atheists really want to make a documentary, they should make one pointing out the gaping holes in the theist's primary arguments.