C.S. Lewis wrote The Screwtape Letters, a fictional series of advice from a senior demon.
The book was published in 1942 and takes the form of letters from Screwtape, an experienced demon, to his inexperienced nephew Wormwood. The letters discuss temptation, distraction, pride, fear, and ordinary human habits from the inverted viewpoint of Hell.
Lewis uses this perspective satirically: the advice is meant to expose the ways people can be misled rather than to provide practical instruction in wrongdoing. The work became one of his most widely read Christian books and helped establish his reputation as a popular religious writer during the Second World War.
Its epistolary format distinguishes it from Mere Christianity, which grew from radio talks, and from The Great Divorce, which uses a dreamlike journey as its narrative framework.