Much of the South, especially the Upland South, was settled by Scots-Irish and Scottish immigrants who were decidedly on the Protestant side of the religious wars in the British Isles during the 17th and 18th Centuries. The same is true for border states like Kentucky, West Virginia, and Missouri, along with the southern one-third of Illinois, Indiana, and Ohio. They are the reverse image of the Irish Catholics, who are heavily concentrated in the Northeast and the Upper Midwest. The two populations of people from the fringes of the British Isles do not overlap too much in this country. In both cases, their religious identity has deep historical roots and conversion from a Protestant denomination to Catholicism and vice versa still carries a social penalty almost 500 years after Martin Luther nailed his 95 Theses to the door of the Wittenburg church.
I can understand completely the social ostracism that can take place when a person is not a part of the dominant religion where they live. But in my case, I was in the minority section. I grew up in Metro Detroit, and honestly, until I was in the 4th or 5th grade, there were NO other Protestant students in my classes. The majority of people were 1st or 2nd-generation Italian and Polish immigrants, who were, of course, Catholic. (This was in the late 60s.) My parents were Methodists from rural Texas, and had moved to the area for better jobs. I remember vividly how the Catholic students were weekly taken by the PUBLIC school buses during school hours for Catechism class. They would be gone from 1 1/2 to 2 hours, while I would sit alone in class twiddling my thumbs (or whatever it is that little girls do. I know I wasn't getting taught at that time.) This practice ended about when I was in 5th grade, as more and more parents objected to the use of public property and funds to provide religious education.
Can you imagine how I was treated by the Catholic majority? I was constantly teased, told I wasn't a Christian, and was excluded from many parties, etc. (And this wasn't just from the kids, either...Where do you think the kids got these ideas from?) So you see, this type of thing can occur anywhere and by anyone. It's funny, for years I WANTED to become Catholic, just so I could be like everyone else. (Although looking back, I wonder if it wasn't because I too wanted to have a big 1st Communion party and get lots of presents...)