According to a Pew Research report, nearly 20% of US resident surveyed (19.6 %), are either atheist, agnostic, or are otherwise not part of a religion (though they may still believe in a deity or spiritual realm). This number has been growing year after year, ever since surveys were first started in the 1970's. The highest growth in the non-religious category has been coming from the younger generations, and one interesting part of the study shows that among the non-religious, when asked if they are looking for a new religion to become a part of, 88% said no.
Maybe America won't be completely taken over by the fundamentalists after all. There's hope now :)