The passage from a lecture of hers which sparked this first for me:
"In 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."
--from "The Fiction Writer and His Country," in Mystery and Manners