Which C.S. Lewis book was adapted from his wartime radio broadcasts about Christian belief?

Mere Christianity was adapted from C.S. Lewis’s wartime radio broadcasts about Christian belief. The broadcasts were delivered by the BBC between 1941 and 1944 and later revised into book form.

Lewis originally presented the talks as a clear defense of shared Christian ideas rather than as an explanation of one denomination’s distinctive doctrines. He discussed morality, human nature, belief, and the meaning of Christian doctrines in language intended for a broad radio audience.

The title can cause confusion because “mere” does not mean insignificant. Lewis used the phrase to suggest the central or common elements of Christianity. The final book was published in 1952, after material from several broadcast series had been edited and arranged into a unified work.