What was the title of C.S. Lewis’s 1942 Christian apologetics book written as demon correspondence?

C.S. Lewis’s 1942 Christian apologetics book written as demon correspondence is The Screwtape Letters.

The book is structured as a series of letters from Screwtape, a senior demon, to his inexperienced nephew Wormwood. Screwtape offers advice about tempting a human being, so the narrative presents moral and spiritual questions from a deliberately inverted perspective. Lewis uses irony to examine pride, distraction, resentment, habit, and self-deception.

The Screwtape Letters first appeared as a newspaper series in the Anglican periodical The Guardian during 1941. The collected book was published in 1942. Lewis dedicated it to his friend J.R.R. Tolkien, though the two authors had different religious and literary projects.

The work is often confused with Mere Christianity because both began partly in wartime religious broadcasting and both explain Christian ideas. They are different forms: Mere Christianity presents arguments directly, while The Screwtape Letters uses fictional correspondence between demons.