Which C.S. Lewis book presents Christianity through radio-talk adaptations?

Mere Christianity presents C.S. Lewis’s explanation of core Christian beliefs through material adapted from wartime radio talks. The book was published in 1952.

Lewis first delivered the talks for the BBC during the Second World War, with broadcasts beginning in 1941. He aimed to explain what he called “mere Christianity”: beliefs shared across many historic Christian traditions rather than the distinctive teachings of one denomination.

The finished book is arranged in four parts: “Right and Wrong as a Clue to the Meaning of the Universe,” “What Christians Believe,” “Christian Behaviour,” and “Beyond Personality.” Some readers mistakenly treat the title as the name of a church or denomination. It is instead a phrase Lewis used for common Christian doctrine, and the book is an edited literary work rather than a transcript of one single broadcast.