Which C.S. Lewis book was adapted from the radio talks he gave during World War II?

Mere Christianity was adapted from radio talks C.S. Lewis gave during World War II.

The BBC broadcast Lewis’s talks between 1941 and 1944, with the aim of explaining basic Christian ideas to a broad audience. Lewis was not trying to present one denomination’s distinctive theology. Instead, he focused on themes shared across historic Christian traditions, including morality, belief, and the person of Christ.

The talks were revised and gathered into three sections: Broadcast Talks, Christian Behaviour, and Beyond Personality. The combined book appeared as Mere Christianity in 1952. Its title refers to the central or shared content of Christianity rather than to a separate church or denomination.

Readers sometimes confuse this book with The Problem of Pain, which was published in 1940 and was written as a continuous theological work rather than assembled from wartime broadcasts. Mere Christianity’s conversational tone and broadcast origin are key parts of its history.