"The Screwtape Letters" is a satirical Christian work by C.S. Lewis, published in 1942. The book is structured as a series of letters from a senior demon, Screwtape, to his inexperienced nephew, Wormwood. Through their correspondence, Screwtape offers advice on how to tempt and corrupt a human soul, illustrating the nature of good and evil. The letters explore various themes, including the challenges of faith, the subtleties of temptation, and the importance of spiritual vigilance. Lewis uses humor and irony to convey profound moral lessons, making the book both entertaining and thought-provoking for readers interested in Christian theology and moral philosophy.