What was the title of C.S. Lewis’s 1942 Christian apologetic book written as letters from a demon?

C.S. Lewis’s 1942 Christian apologetic book written as letters from a demon is The Screwtape Letters. The book presents a series of fictional instructions from Screwtape, an experienced demon, to his inexperienced nephew Wormwood.

Rather than giving direct advice from a human or angelic narrator, Lewis uses the demonic correspondence to examine temptation, distraction, pride, resentment, and self-deception. The inversion creates irony: readers infer Christian moral principles from advice intended to lead a human away from them.

The book first appeared during the Second World War and was initially published in serial form in the Anglican newspaper The Guardian. Its title character is Screwtape, while Wormwood is the junior tempter. The work is distinct from Mere Christianity, which developed from radio talks, and The Great Divorce, which is a separate imaginative theological work.