I always enjoy reading things like this list of the Top 50 Atheism Quotes. Since their number one quote is from George Carlin, and it sounds so much better in his own voice, here it is for anyone that has not already watched this segment.
However, in this case, I must say that I was a bit disappointed that they did not include the quote by Pierre-Simon Laplace (of Laplace Transformation fame) when speaking to Napoleon. Perhaps it was omitted because it is usually misquoted a tad and may not even have a perfectly accurate translation to English. However, since it is one of my personal favorites, I hope that you will read the details of the Laplace and Napoleon encounter on wikipedia.
I was also disappointed that they did not include any quotes from Robert Heinlein. So, I also hope you will click to read these quotes about religion from Robert A. Heinlein.
Thanks to rit for the link to the list that started this post!