Which BBC radio-talks book made C.S. Lewis widely known during World War II?

Mere Christianity grew out of the BBC radio talks that made C.S. Lewis widely known during World War II. The talks were broadcast between 1941 and 1944 and were later revised and published as a book.

Lewis presented a broad defense of Christian belief rather than focusing on one denomination. The book discusses morality, Christian doctrine, and the meaning of faith in language intended for a general audience. Its title reflects Lewis’s aim to describe shared Christian ideas rather than the distinctive practices of a particular church.

The work was not originally delivered as a single book. The first series became The Case for Christianity, followed by Christian Behaviour and Beyond Personality; these were later combined and revised as Mere Christianity. The radio broadcasts helped establish Lewis as one of the most prominent Christian public intellectuals of his era.