Which radio talks by C.S. Lewis were collected as Mere Christianity?

Mere Christianity grew out of C.S. Lewis’s BBC radio broadcasts.

Lewis delivered the talks during the Second World War, beginning in 1941. He spoke to a broad public audience about shared Christian beliefs rather than presenting the distinctive doctrines of one denomination. The broadcasts were later revised and collected in book form, first as Broadcast Talks and then in the expanded volume titled Mere Christianity.

The work is therefore neither a transcript of university lectures nor a record of Inklings meetings. Its accessible style reflects the original radio format: Lewis aimed to explain difficult ideas in language that ordinary listeners could follow. The book’s title refers to what Lewis saw as the common core of historic Christianity, rather than to a separate church or denomination.