Which C.S. Lewis book developed from his BBC radio broadcasts during World War II?

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

Lewis delivered a series of radio talks between 1941 and 1944, explaining and defending basic Christian beliefs for a general audience. The talks were later revised and collected in book form as Mere Christianity. The title refers to the common core of belief shared across historic Christian traditions rather than to one denomination.

The book is organized into sections that discuss morality, Christian belief, and Christian behavior. Lewis’s conversational style helped make difficult philosophical and theological ideas accessible to listeners who were not specialists.

Mere Christianity is sometimes mistaken for a direct transcript of the broadcasts. Lewis revised the material for publication, and the final book reflects changes in wording and arrangement. It also differs from The Problem of Pain, an earlier book that addresses suffering and the problem of evil.