America and the founding fathers may not be "Christian" but we put "in God we trust" on the money for a reason. The founding fathers never said they wanted everyone to be atheist, just that they could worthship their own personal God. Notice how it doesn't say "in Gods we trust". None of the founding fathers believed in old disproven pagan Gods.
Of course I believe people should be allowed to be atheist, or pagan (just because quantum physics proves ther is a God doesn't mean people should be forced to believe in Him). I just don't think America is an atheist or pagan country just because some people are that way. That would be like saying we are a racist country just because some people are racist.
America is a democracy, and if we all voted, I think we would be overall christian and overall not racist.