South Park: Go, God, Go! Part II
Mrs. Garrison: Pound my monkey hole, Richard!
I figured Matt and Trey would at least lean toward the side of evolution in this episode, and they did, but it was really about how we tend to oversimplify things. Mr. Garrison reluctantly teaches evolution, telling the kids they're basically all "retarded fish squirrels," the product of a millenia's worth of inter-species butt sex. Later, author and atheist Richard Dawkins automatically turns Garrison into an atheist by telling him that a flying spaghetti monster is as likely to exist as God because you can't disprove either.
The episode later asks the question, if everyone were atheist, would that make the world any better? The answer seems to be no, because in the future different atheist sects will pop up and wage war on one another. Also, sea otters who threaten to crack open Eric's skull like a clam on their tummy.
The nice little nod to The Shining when Cartman freezes himself.
The future atheists ironically turning atheism into a religion of its own, saying things like, "science damn you!" rather than "god damn you!"