Her faith was part of her writing. She was an original disruptor! I found this from a piece in The Atlantic: 

In O’Connor’s story Revelation, for instance, the pious Mrs. Turpin is attacked by an insane girl in a doctor’s waiting room. “Go back to hell where you came from, you old wart hog,” the girl tells her. Later, while hosing down her pigs—divinely concussed, so to speak—Mrs. Turpin has a vision: a cavalcade moving toward the crack of heaven, a “vast horde of souls” led by “white-trash, clean for the first time in their lives,” and “battalions of freaks and lunatics shouting and clapping and leaping like frogs.” These are the poor in spirit, coming into their inheritance. Bringing up the rear, meanwhile, are the righteous, the organized, the scrupulous and stainless, the people like Mrs. Turpin and her husband. “They were marching behind the others with great dignity … Yet she could see by their shocked and altered faces that even their virtues were being burned away.”

HA!