Which C.S. Lewis book grew from his BBC radio broadcasts about Christianity?

Mere Christianity grew from C.S. Lewis’s BBC radio broadcasts about Christianity.

Lewis delivered the talks during the Second World War, beginning in 1941. The broadcasts were intended for a broad audience and presented shared Christian ideas rather than the distinctive doctrines of one denomination.

The talks were later revised and published in book form. Mere Christianity became one of Lewis’s most influential works of Christian apologetics, especially in the English-speaking world. It discusses morality, belief, Christian doctrine, and the practical implications of faith.

The title does not mean “weak” or “minimal” Christianity. Lewis used “mere” in the older sense of basic or essential Christianity: beliefs held across major Christian traditions. The book is distinct from The Problem of Pain, which appeared in 1940 and addresses suffering and divine goodness.