It's always wrong of course to say that you can't do this or you can't do that in fiction. You can do anything you can get away with, but nobody has ever gotten away with much.
Flannery O'ConnorMost of us have learned to be dispassionate about evil, to look it in the face and find, as often as not, our own grinning reflections with which we do not argue, but good is another matter. Few have stared at that long enough to accept that its face too is grotesque, that in us the good is something under construction. The modes of evil usually receive worthy expression. The modes of good have to be satisfied with a cliche or a smoothing down that will soften their real look.
Flannery O'ConnorIn the greatest fiction, the writer's moral sense coincides with his dramatic sense, and I see no way for it to do this unless his moral judgement is part of the very act of seeing, and he is free to use it. I have heard it said that belief in Christian dogma is a hindrance to the writer, but I myself have found nothing further from the truth. Actually, it frees the storyteller to observe. It is not a set of rules which fixes what he sees in the world. It affects his writing primarily by guaranteeing his respect for mystery.
Flannery O'Connor