NPR Essay: There is No God: "Just the love of my family that raised me and the family I'm raising now is enough that I don't need heaven. I won the huge genetic lottery and I get joy every day."
Penn Jillette is pretty set in his (dis)belief, but it seems less of a philosophical argument and more of a cutesy fingers-in-the-ears, singing-at-the-top-of-my-lungs perspective. He feels he won the gentic lottery - What's not clear is how this belief system for the rest of the world who are lottery losers.
Check out the whole essay. There are a few links at the bottom of the page for other essays on the same topic. Fascinating - and often sad - reading.