I like funny infographics. Here’s one:
(From here. L-R, T-B: Ernest Hemingway, Abraham Lincoln, Carl Sagan, Mark Twain, Thomas Jefferson, Benjamin Franklin, Albert Einstein, Charles Darwin.)
Now, you might argue that not all the men pictured here were really atheists. While it is true that people like Thomas Jefferson, Abraham Lincoln, and Benjamin Franklin did believe that there was probably some sort of god, it was only because scientific knowledge in that day was so lacking.
In the 18th and first half of the 19th century, there was no theory of evolution, or the big bang. It would have been very difficult to reject the Christian belief that god created everything, when there was no real alternative theory that could explain everything. If you could somehow bring these people into the 21st century, and teach them all that science has discovered along with the vast bulk of evidence that goes along with it, I’m almost certain they would accept it.
What we do know for certain is that all the people pictured were not faithful Christians, or believed in a personal god. And that they were at least adherents to rational thought and skepticism, which is the most important thing of all.