The talks that became C.S. Lewis’s Mere Christianity were first broadcast on the BBC.
During the Second World War, Lewis delivered a series of radio talks for the BBC. The broadcasts were intended to explain and defend basic Christian ideas in language accessible to a broad British audience. Their success led to revised versions being published in book form.
Mere Christianity was assembled from three broadcast series: The Case for Christianity, Christian Behaviour, and Beyond Personality. Lewis later revised the material, and the combined book appeared in 1952. The title refers to the shared core of Christian belief rather than to one particular denomination.
The book is sometimes described as a transcript of the broadcasts, but it is more accurate to say that it grew out of them and was substantially edited for publication. Lewis’s clear radio style helped establish his reputation as a public Christian apologist well beyond Oxford’s academic circles.