Which C.S. Lewis book was adapted from his 1941 BBC radio talks on Christianity?

Mere Christianity was adapted from C.S. Lewis’s 1941 BBC radio talks on Christianity.

The original broadcasts were delivered during the Second World War, when the BBC sought speakers who could address a broad public audience. Lewis presented a series of short talks explaining shared Christian ideas in accessible language rather than arguing for one denomination’s distinctive doctrines.

The talks were later revised and collected in book form. Mere Christianity is organized into sections commonly titled “Right and Wrong as a Clue to the Meaning of the Universe,” “What Christians Believe,” “Christian Behaviour,” and “Beyond Personality.”

The title does not mean a reduced or casual version of Christianity. Lewis used “mere” to refer to the central beliefs held across historic Christian traditions. Readers sometimes confuse the book with The Problem of Pain, which was a separate work published in 1940.