Which BBC radio talks became the basis for C.S. Lewis’s Mere Christianity?

C.S. Lewis’s Mere Christianity grew out of a series of BBC radio broadcast talks.

Lewis delivered the talks during the Second World War, beginning in 1941, when the BBC was seeking clear religious programming for a broad public audience. He spoke without relying on academic jargon, presenting arguments about morality, Christian belief, and the meaning of faith.

The broadcasts were later revised and assembled into books, eventually forming Mere Christianity, first published in book form in 1952. The title refers to the shared core of Christian belief rather than to one denomination. It is sometimes mistaken for a university lecture series because Lewis was an Oxford academic, but its original public form was radio broadcasting.