Which C.S. Lewis book developed material from his wartime BBC broadcasts?

Mere Christianity developed material from C.S. Lewis’s wartime BBC broadcasts.

Lewis delivered a series of talks for BBC Radio during the Second World War, beginning with The Case for Christianity in 1941. Further broadcasts followed in 1942 and 1944, and the material was later revised and collected as Mere Christianity.

The book presents a broad defense of central Christian beliefs rather than an argument for one particular denomination. Its chapters discuss morality, Christian doctrine, and the virtues of faith, hope, and charity. Lewis’s conversational radio style helped make difficult religious ideas accessible to a wide audience.

The title does not mean “minimal” Christianity in a dismissive sense. Lewis used “mere” to refer to the shared core of belief he believed united historic Christian traditions. The book remains one of his most widely read works of Christian apologetics and helped establish his public reputation beyond literary scholarship.