Below you see an image of the latest results of an extensive survey conducted by Pew Forum. The survey asked a very large sample 35K+ people questions about their religious beliefs. After looking through the survey results I found this part quite humorous.
515 self identified atheists were asked the following question: Do you believe in God or a universal spirit? [IF YES, ASK:] How certain are you about this belief? Are you absolutely certain, fairly certain, not too certain, or not at all certain? 41 atheists said they were absolutely certain God exists, 36 said they were fairly certain, and 31 said they were not too certain. So 108 out of 515 atheists did not deny that God exists.
Next time you hear the results of a poll, always remember there is a good chunk of the population that has no clue what they are talking about or how to even correctly identify themselves.
You can view the results of the survey by clicking here.