Which C.S. Lewis book grew out of his BBC radio broadcasts about basic Christian beliefs?

Mere Christianity grew out of C.S. Lewis’s BBC radio broadcasts about basic Christian beliefs. The broadcasts were delivered between 1941 and 1944, during the Second World War, and later revised and collected in book form.

Lewis intended the work to explain what he called “mere Christianity”: beliefs shared across major Christian traditions. The book discusses morality, human reasoning, Christian doctrine, and the significance of Jesus, while avoiding detailed disputes between denominations.

The published work is arranged in four books: “Right and Wrong as a Clue to the Meaning of the Universe,” “What Christians Believe,” “Christian Behaviour,” and “Beyond Personality.” The radio talks made Lewis widely known beyond academic circles.

A common misunderstanding is that Mere Christianity is a single transcript of one speech. It is instead a revised book assembled from several broadcast series, and its title refers to shared core beliefs rather than to a denomination called Mere Christianity.