C.S. Lewis began the BBC radio talks later published as Mere Christianity in 1941.
The first series was broadcast in 1941 during the Second World War. Lewis was invited to speak about Christianity to a broad radio audience, and his talks were designed to be accessible rather than aimed at specialists. He later presented additional broadcasts in 1942 and 1944.
The published book was assembled from revised versions of these broadcasts. Its title refers to the shared or basic beliefs held across many Christian traditions, rather than to a separate denomination. Lewis discusses morality, belief, Christian doctrine, and the implications of following Christ.
The book is sometimes treated as if it were written from the start as a conventional theological volume. Its origins as spoken radio addresses help explain its direct style and frequent use of everyday examples. The broadcasts made Lewis widely known beyond Oxford’s academic and literary circles.