Which C.S. Lewis book presents arguments through letters written by a senior demon?

The Screwtape Letters presents arguments through letters written by the senior demon Screwtape.

Published in 1942, the book is structured as correspondence from Screwtape to his inexperienced nephew Wormwood. Screwtape offers advice on tempting a human patient, while Lewis uses the demonic viewpoint to explore habits, distraction, pride, fear, and moral self-deception.

The letters are satirical rather than a conventional supernatural adventure. Their central technique is inversion: readers are expected to recognize that the demons’ goals are harmful and that their apparently strategic advice exposes common human weaknesses. The book’s Christian arguments are therefore delivered indirectly through irony.

The title refers to the correspondence format and to its principal writer. Lewis later wrote a short sequel, “Screwtape Proposes a Toast,” which was published separately before appearing in editions alongside the original work.