Which C.S. Lewis book began as BBC radio talks broadcast during World War II?

Mere Christianity began as BBC radio talks broadcast during World War II.

C.S. Lewis delivered the first series, titled “The Case for Christianity,” in 1941. Further broadcasts followed under the titles “Christian Behaviour” and “Beyond Personality.” The talks were aimed at a broad British audience during wartime, and Lewis used direct, conversational language rather than the style of a formal academic lecture.

The material was later revised and collected as Mere Christianity, first published as a book in 1952. The title refers to the shared core of Christian belief that Lewis believed existed across major Christian traditions, rather than to a separate denomination.

The book is often confused with The Problem of Pain, another major Christian work by Lewis, published in 1940. Mere Christianity’s distinctive origin as wartime broadcasts helped make it one of Lewis’s most widely read works.