What was the title of C.S. Lewis’s 1952 book adapted from his BBC radio talks?

The title of C.S. Lewis’s 1952 book adapted from his BBC radio talks is Mere Christianity. The book presents a case for shared Christian beliefs rather than defending one particular denomination.

The material began as three series of radio broadcasts during the Second World War: Broadcast Talks, Christian Behaviour, and Beyond Personality. Lewis revised and combined them for publication, producing Mere Christianity in 1952.

The book is organized around moral law, Christian belief, and the practical meaning of Christian conduct. Its opening argument uses the idea of a common moral law as evidence that humans recognize standards they often fail to keep.

“Mere” in the title does not mean shallow or insignificant. Lewis used it to indicate the common or central beliefs shared across historic Christian traditions. The book therefore differs from The Problem of Pain, which concentrates more specifically on suffering and the existence of God.