In O'Connor's short stories, including "A Good Man is Hard to Find," no one is a deep thinker: all are flat, static "wingless chickens" who care only for the material world, not the spiritual one.  Remember, O'Connor is a comic writer: a spiritual satirist.  She believes in the opposite of what her characters do.

In her stories all have fallen from grace; all are blind to their spiritual doom.  When reading O'Connor's prose one can feel the laws of attraction at work: good begets good; evil begets evil. Syntheses and concessions are pitfalls. Either one is Christ-centered or hell-bent toward the fumes of the gas chamber. Her poles are distinct and opposing, the slippery slope a descent to hell.

Her comic religious vision holds that a morally and socially degenerate (like the Misfit) is nonetheless spiritually a cut above the wingless chickens of privileged Christianity (the grandmother and her family). She shocks her readers by beginning with divine evil (the Misfit's murders) as a backdoor to what is divine good so that they may rediscover what is holy (to not take salvation for granted). Her goal, I think, is to prevent her readers from taking sides among her religious forms; instead, she calls for action--from them to be seekers instead of being found.

In the story it's the Misfit vs. the grandmother.  While the latter characterizes the former as "a good boy," the Misfit acknowledges the modern man's spiritual predicament, an echo of Dostoevsky's "If there is no God, then anything is permissible," when he says:

Jesus was the only One that ever raised the dead and He shouldn't have done it. He shown everything off balance. If He did what He said, then it's nothing for you to do but thow away everything and follow Him, and if He didn't, then it's nothing for you to do but enjoy the few minutes you got left the best way you can--by killing somebody or burning down his house or doing some other meanness to him. No pleasure but meanness.

Instead of having her characters "follow Him," she has them all "enjoy the few minutes [they] got left" by "killing," "burning down" houses, and "other meanness."  Not exactly deep thinking...