What is the title of C.S. Lewis’s 1942 book defending Christianity through fictional letters from a demon?

C.S. Lewis’s 1942 book of fictional demonic correspondence is The Screwtape Letters.

The book consists of letters from Screwtape, an experienced demon, to his younger nephew Wormwood. Screwtape advises Wormwood on how to tempt and mislead a human patient. Lewis reverses the expected viewpoint: readers see ordinary moral and spiritual weaknesses through the strategic language of Hell rather than through a conventional narrator.

The work first appeared in serialized form in the Anglican newspaper The Guardian in 1941, before book publication in 1942. It is not a conventional theological treatise, although it addresses Christian ideas about temptation, pride, distraction, prayer, and repentance. The fictional format also distinguishes it from Mere Christianity and The Problem of Pain, which present arguments in a direct expository voice. Lewis later expressed some reservations about the book’s tone because of its satirical premise.