What was the title of C.S. Lewis’s 1942 work written as letters from a senior demon?

C.S. Lewis’s 1942 work written as letters from a senior demon is The Screwtape Letters.

The Screwtape Letters is a satirical Christian apologetic work presented as correspondence from Screwtape, an experienced demon, to his inexperienced nephew Wormwood. Screwtape advises Wormwood on how to tempt and mislead a human patient. The reversed perspective allows Lewis to examine ordinary habits, self-deception, distraction, pride, and spiritual complacency.

The book first appeared in serialized form in the Anglican newspaper The Guardian, beginning in May 1941, and was published in book form in 1942. Lewis later said that writing from a demonic viewpoint was difficult and unpleasant because it required maintaining the perspective of a hostile intelligence.

Despite its fictional format, the work is not a demonology manual. Its humor depends on dramatic irony: readers are expected to recognize that Screwtape’s advice reveals the weaknesses he wants to exploit.