I can't say personally as I never lived down South, but folks I've known that did have told me they experienced similar in smaller towns with members of the predominant denomination there. Keeping it all in the family so to speak. Outsiders only marginally welcome, unless it impacts their Church's members, then they're not welcome at all.
Same/same in my opinion (now the holy wrath from the Southern Baptists will rain upon us ;-) ). I’ve experienced it living in Texas, but also in small towns in Europe. It’s something we used to train exchange students to be aware of.
