From my experiences, it is a mixed bag. I grew up in Columbia, SC with a highly religious mom and a southern baptist preacher uncle. I've never been religious myself and I've never had anybody harp on me for it. From what I've seen/heard, nobody really cares if you are atheist, but you can catch major s*** for practicing other religions. I've had plenty of arguments with friends and family over terrible things they've said about other religions.
But I don't see it as a hallmark of the South. More of a universal human characteristic.
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