Which C.S. Lewis work was adapted from BBC radio broadcasts?

Mere Christianity was adapted from C.S. Lewis’s BBC radio broadcasts.

Lewis delivered the talks during the Second World War, beginning in 1941. The broadcasts addressed basic Christian beliefs in language intended for a broad radio audience, not only for specialists or members of one denomination. Their popularity led Lewis to revise and combine the material for book publication.

The resulting book appeared in 1952. It is organized around themes such as morality, Christian belief, and the virtues, and it presents what Lewis called “mere Christianity”: core ideas shared across many historic Christian traditions.

The work is sometimes mistaken for The Problem of Pain, which Lewis published in 1940, or Miracles, published in 1947. Neither originated as the famous wartime BBC broadcast series. Mere Christianity’s broadcast history explains its direct, conversational style and its lasting popularity as an introduction to Lewis’s apologetic writing.