What radio program series formed the basis of C.S. Lewis’s Mere Christianity?

C.S. Lewis’s Mere Christianity developed from BBC radio talks.

Lewis delivered the talks during the Second World War, beginning with a series broadcast in 1941. He was invited by James Welch, the BBC’s Director of Religious Broadcasting, to explain basic Christian belief to a broad audience. Lewis’s calm, conversational style made the broadcasts accessible beyond academic and church settings.

The talks were revised and collected in stages. Broadcast material became The Case for Christianity, Christian Behaviour, and Beyond Personality. These sections were later combined and edited into the book Mere Christianity, whose title refers to the shared core of traditional Christian belief rather than to a particular denomination.

The radio format shaped the work’s plain language, analogies, and direct address. It was not originally written as one continuous book, and readers sometimes assume that it began as a single manuscript. Its structure reflects the development from separate broadcasts into a unified apologetic volume. The book remains one of Lewis’s most frequently read works.