You might be surprised about places other than SoCal and NY NY. Like growing up in Tennessee Alabama and Georgia, everyone seemed to have some affiliation. The level of engagement varied, but I never met someone that was an openly staunch atheist in real life. There is a deep stigma about such a thing in the South, - sadly. There, even extremists like Church of God are nominalized (screaming you're going to hell for an hour, exorcism/miracle drama nonsense, mobbing behaviors, religious masochism).

It is likely one would need to be second or third generation removed from and religious social support network in a family unit before a person would truly answer atheist on such a poll. I don't think many people grow to the point of self awareness to care to define an anti religious god certainty at this stage in human cultural evolution.

[–] seeking_perhaps@mander.xyz 2 points 21 hours ago

While I have not lived in the south I do have some deeply religious and conservative family members, so I do see where you're coming from. I just think even a good chunk of the people you mentioned have an affiliation to fit in and not because they are genuinely religious, i.e. pray regularly and go to church every Sunday. In other words, it's a cultural thing. They probably wouldn't go so far as to consider themselves atheist, but I could easily see them considering themselves culturally Christian and non-religious in practice. I have no idea what percentage that actually breaks down to, but my guess is it's a decent amount lower than 70%.