Which C.S. Lewis work developed from his 1941 BBC radio broadcasts?

Mere Christianity developed from C.S. Lewis’s 1941 BBC radio broadcasts.

The broadcasts were called Broadcast Talks and were intended for a broad British audience during World War II. Lewis explained basic Christian ideas in plain language, beginning with moral law and moving toward questions about belief, repentance, and Christian life.

The talks were later revised and collected into book form. The title Mere Christianity refers to the shared core of belief held across historic Christian traditions, rather than to one denomination’s distinctive doctrines.

Lewis was not presenting a complete systematic theology, and the book does not try to settle every disagreement among churches. Its conversational style and radio origins helped make it one of his most influential works of Christian apologetics.