Which C.S. Lewis book presents a Christian allegory through a conversation between a demon and his nephew?

The Screwtape Letters is C.S. Lewis’s Christian allegory presented as correspondence from the senior demon Screwtape to his inexperienced nephew Wormwood. The book was first published in 1942 during the Second World War.

Each letter offers advice on tempting a human “patient,” allowing Lewis to examine pride, distraction, self-deception and spiritual complacency from an inverted perspective. The demonic viewpoint is satirical rather than a claim that Lewis endorsed the demons’ reasoning.

A common mistake is to identify Wormwood as the narrator. Screwtape writes the letters, while Wormwood is the junior tempter who receives them. The framing device gives the book its distinctive voice and lets Lewis criticize human habits indirectly.

The work began as a series in the Anglican newspaper The Guardian before appearing in book form. Lewis later added a short concluding piece, “Screwtape Proposes a Toast,” which was published separately and then included in many editions. The Letters remains one of his most frequently adapted and discussed apologetic works.