Which C.S. Lewis book presents his Christian beliefs as a series of radio talks?

Mere Christianity presents C.S. Lewis’s Christian beliefs in a book developed from radio talks. The broadcasts were delivered for the BBC during the Second World War, and Lewis later revised them into the familiar volume.

The talks were intended for a broad listening audience rather than an academic theological readership. Lewis explained basic Christian ideas through arguments about morality, human behavior, forgiveness, and the nature of God. His conversational style helped make the broadcasts widely accessible.

The book is divided into four parts: “Right and Wrong as a Clue to the Meaning of the Universe,” “What Christians Believe,” “Christian Behaviour,” and “Beyond Personality.” The title refers to shared or “mere” Christianity—the beliefs held in common by many historic Christian traditions.

Mere Christianity is sometimes mistaken for a direct transcript of one uninterrupted radio series. It is a later book assembled and revised from multiple broadcast series, including material first published as Broadcast Talks and Christian Behaviour.