Which C.S. Lewis book presents correspondence from a senior demon to a junior tempter?

The C.S. Lewis book presenting correspondence from a senior demon to a junior tempter is The Screwtape Letters. It was published in book form in 1942 and is written as a series of fictional letters.

The senior demon Screwtape advises his inexperienced nephew, Wormwood, about tempting a human being. Lewis reverses ordinary moral language: the demons call God “the Enemy,” while their own master is “Our Father.” This satirical viewpoint lets Lewis examine pride, distraction, vanity, fear, and spiritual complacency.

The book began as a wartime concept and was connected with Lewis’s radio work and Christian apologetics. Unlike a conventional novel, it has no continuous scene-by-scene plot. Its structure depends on the letters and the gradual course of the unnamed patient’s life.

The title is sometimes confused with The Great Divorce, another Lewis work about the afterlife and spiritual choices. The Screwtape Letters is distinct for its epistolary form and its deliberately inverted perspective.