Please learn about statistical significance, and sample size and confidence levels. For a population of 350 million, you only need a sample size of about 2400 to gain a confidence level of 95%.As another American, I have to ask where you are getting your info from? If it is that crackpot Gallup Poll, don't rely on it as 'factual'. I would have to double check, but I think they polled 3,000(ish) people....hardly a decent sampling. You'd do better with The Pew Research Center.
Both reports agree that religion is declining, but it is no where near as low as Gallop is claiming (over all, not region specific). Christians are down to 65% (from 77% a decade ago), while religiously unaffiliated (atheist, agnostic or “nothing in particular,”) now stands at 26%, up from 17% in 2009".
So if you don't know, just don't...