Two quotes from Flannery O'Connor:

"The type of mind that can understand good fiction is not necessarily the educated mind, but it is at all times the kind of mind that is willing to have its sense of mystery deepened by contact with reality, and its sense of reality deepened by contact with mystery."

"The sorry religious novel comes about when the writer supposes that because of his belief, he is somehow dispensed from the obligation to penetrate concrete reality ...But the real novelist, the one with an instinct for what he is about knows that he cannot approach the infinite directly, that he must penetrate the natural human world as it is."