Which book grew out of C.S. Lewis’s wartime radio broadcasts?

Mere Christianity grew out of C.S. Lewis’s wartime radio broadcasts.

Lewis delivered a series of talks for the BBC during the Second World War, beginning in 1941. The broadcasts were intended for a general audience rather than an academic one, and they explained basic Christian ideas in direct, conversational language.

The talks were later revised and published in book form. The resulting volume, Mere Christianity, is arranged in four broad parts: “Right and Wrong as a Clue to the Meaning of the Universe,” “What Christians Believe,” “Christian Behaviour,” and “Beyond Personality.”

The title does not refer to a separate denomination founded by Lewis. “Mere Christianity” means the core beliefs shared across historic Christian traditions. The book is therefore an apologetic work, not a memoir or a fictional narrative, and its origin in radio explains its accessible style.