I was born in the south and lived here for nearly 30 years now. I think a lot of it is how you approach things. Most southern people are live and let live. Doesn't matter who or what you are, you treat people with kindness and respect. But if someone does something they deem disrespectful, that's when they get two-faced. Don't talk about how stupid you think religion is. Don't talk about how horrible X or Y politician is. That is potential to disrespect an opinion someone else might have. If you don't like something, you gotta be polite about it. e.g., if you don't like Trump, the correct way to voice it is: "I don't much care for his attitude/policies." Incorrect way: "Trump is a fucking idiot and I can't believe anyone would support such an awful person."
And if someone has an opinion you disagree with, still be polite about it. Some old lady says, "I can't believe her daughter married that black boy. What was she thinking?" Don't say, "Wow, that's so fucking racist. I can't believe you think that." Instead, you can phrase it like, "Personally, I don't think it's a big deal. Lots of people are okay with that now. The world's not the way it used to be." The phrasing infers that "the world is changing and not everyone shares your opinion." vs. "I personally think you're a horribly racist bigot." Let the old lady know that you personally think she's a bag of dicks and yeah, she's gonna throw shade at you.
To people who don't grow up in this culture, it might all seem fake and disingenuous, but I'd have to disagree. You can certainly have strong opinions, disagree with people, etc. but you just have to phrase it in a "polite" manner. As long as you're courteous to everyone - even when you disagree with them - then you'll likely be treated the same. If you're just blunt to everyone about everything without caring about how it comes across, then yeah. You're going to be swimming in a sea of passive aggression. Especially if you're a yank.