I am of the totally unsubstantiated opinion that there are far more atheistic attitudes in the bible belt then anyone could possibly contemplate or indeed realise.

A very significant pressure is to not be a target or singled out from the crowd.

Anonymity is in camouflage...in a society that is seemingly dominated by religion it would be safer to pretend then to actually take it seriously. No one says a word to anyone, not even family members, not a hint...fear is a powerful and unforgiving tool of the oppressor. The ironic thing would be that if everyone felt that way then presumed peer pressure would result in a significant percentage that are keeping stum...even from each other.! A typical Baptist church might harbour over 50% atheists on any single Sunday...now that would be weird...and ultimately extremely sad if not poignant.

But as I say...this scenario is unevidenced...but they say fact is far stranger then fiction.