What was the title of C.S. Lewis’s 1942 book presenting Christian ideas through letters from a demon?

The Screwtape Letters is C.S. Lewis’s 1942 book presenting Christian ideas through letters from a senior demon.

The fictional letters are written by Screwtape, an experienced tempter, to his nephew Wormwood, who is assigned to influence a human being. Because the advice is presented from the demons’ perspective, Lewis uses irony to expose temptation, pride, distraction, resentment, and self-deception.

The book was first published in book form in 1942 after portions had appeared in the Anglican newspaper The Guardian. Its unusual format made theological and moral discussion accessible to a broad audience, while also allowing Lewis to criticize common human habits indirectly.

The letters are not a handbook of occult practice and do not present demons as reliable authorities. Their persuasive force comes from reversal: readers infer Christian moral lessons by seeing destructive strategies described approvingly by the fictional tempter.