There are two equal and opposite errors into which our race can fall about the devils. One is to disbelieve in their existence. The other is to believe, and to feel an excessive and unhealthy interest in them. They themselves are equally pleased by both errors and hail a materialist or a magician with the same delight.
Readers are advised to remember that the devil is a liar. Not everything that Screwtape says should be assumed to be true even from his own angle. I have made no attempt to identify any of the human beings mentioned in the letters; but I think it very unlikely that the portraits, say, of Fr. Spike or the patient’s mother, are wholly just. There is wishful thinking Hell as well as on Earth. [From the Preface to The Screwtape Letters, by C. S. Lewis]