The Screwtape Letters

The Screwtape Letters is a satirical Christian apologetics novel written in epistolary style by C. S. Lewis, first published in book form in February 1942. The story takes the form of a series of letters from a senior demon, Screwtape, to his nephew, a junior "tempter" named Wormwood, so as to advise him on methods of securing the damnation of a British man, known only as "the Patient".
The Screwtape Letters is one of Lewis' most popular works, although he claimed that it was "not fun" to write, and "resolved never to write another 'Letter'."