Which C.S. Lewis book collects his wartime radio talks later known as Mere Christianity?

Mere Christianity collects C.S. Lewis’s wartime radio talks under the title Mere Christianity.

Lewis delivered the original broadcasts for the BBC during the Second World War, beginning in 1941. The talks were later revised and published in stages as Broadcast Talks, Christian Behaviour, and Beyond Personality before being combined as Mere Christianity in 1952.

The book presents an argument for shared core Christian beliefs rather than a detailed defense of one denomination. Its famous discussions include morality, human nature, repentance, and the meaning of Christian faith. The “mere” in the title means the central beliefs held across historic Christianity.

The book is sometimes incorrectly treated as a verbatim transcript of the broadcasts. Lewis edited and reorganized the material for print, so the final volume reflects both the radio talks and later revisions.