The best thing I ever read on [Graham] Greene was written by an English girl named Elizabeth Sewell and was published in Thought. She allowed that his sensibility was different from his convictions, the former being Manichean and the latter Catholic, and of course, you write with the sensibility. Her word for him was Neo-Romantic Decadent. What he does, I think, is try to make religion respectable to the modern unbeliever by making it seedy. He succeeds so well in making it seedy that then he has to save it by the miracle.
Letter to Maryat Lee, January 31, 1957, The Habit of Being: Letters of Flannery O'Connor --via just a reader aka Bookish Gardener