Well, before they lost the Civil War they believed that "states rights" should apply to the administration of slavery but not the non-administration of slavery (the Fugitive Slave Laws). The hypocrisy runs deep.

Such “beliefs” are cooked up by people who are mostly self-serving and insincere. We’d call them “political operatives” today I guess.

Unfortunately other people hear the ideas, internalize them, and repeat them, without recognizing any contradictions.