Which BBC radio talks by C.S. Lewis were collected into a book called Mere Christianity?

Mere Christianity grew from C.S. Lewis’s BBC radio broadcasts during World War II.

Lewis delivered the talks between 1941 and 1944, and the broadcasts were later revised and collected in book form. The talks explained basic Christian beliefs in language intended for a broad radio audience rather than only for theologians or academics.

The book is organized into four sections: “Right and Wrong as a Clue to the Meaning of the Universe,” “What Christians Believe,” “Christian Behaviour,” and “Beyond Personality.” Lewis used the phrase “mere Christianity” for the central beliefs shared across historic Christian traditions.

The work is sometimes described as a single set of wartime lectures, but it developed across several broadcast series. Its origin in wartime radio helped give it an unusually direct style, and the book later became one of Lewis’s most influential works of Christian apologetics.