I'm not sure I know a true Atheist, as I think most people I know agree that there is a God...or at least a supreme being to get this ball of wax going. This is not a creation vs. big bang theory debate. This is about not believing in God.
Our church went through a series about Christian Atheists. The concept is, you believe in God...but you live as if He doesn't exist. I got out of it that the attitude that Christians are hypocritical is somewhat true. We all have our area that we don't want to give up, for whatever reasons. There are some things that we hand over to God, but there is your "secret stash" that you don't want God coming in and telling you that you need to stop doing "that".
I believe we all have crap, just some are better at hiding it. We all fall short. We are human. It's just a question of do you admit your errors, and go back to Him.
The good news is, now matter how "bad" you think your crap is...God doesn't care. He's there EVERY TIME. His arms are open, and He is saying, "Come on home. I've been waiting for you."