Which C.S. Lewis book was adapted from his 1941 BBC broadcasts and published in 1952?

Mere Christianity was adapted from C.S. Lewis’s 1941–1944 BBC broadcasts and published as a book in 1952. The work presents what Lewis considered the central beliefs shared by the major Christian traditions.

The book developed from three broadcast series: The Case for Christianity, Christian Behaviour, and Beyond Personality. Lewis used direct, conversational language for radio listeners, then revised and combined the material for publication. The final title refers to basic Christianity rather than to a particular denomination.

The book is organized into four sections, covering moral law, Christian belief, Christian behavior, and the doctrine of the Trinity. Its famous opening argument about a universal moral law is one reason the work remains widely cited.

Mere Christianity is often confused with The Problem of Pain because both are apologetic works. The key distinction is publication history: The Problem of Pain appeared in 1940, before the BBC broadcasts, while Mere Christianity grew directly out of them.