I keep seeing these polls about the percentage of Americans who believe in God...?

I'd say the figures are close to accurate. You know a lot of atheists because you gravitate toward like-minded individuals. That's not an insult, it's just human nature: veterans have VFW posts and squadron reunions because of similarities in experiences; fans have Elvis and Beatles and Star Trek conventions, etc. However, simply because there are 75,000 Elvis fans in Memphis on August 16th doesn't mean that everyone in the world loves Elvis. It doesn't even mean that everyone in MEMPHIS loves Elvis. Same thing with atheism: just because everyone you know is an atheist doesn't mean the entire world shares your views.