C.S. Lewis’s BBC talks later published as Mere Christianity were originally titled Broadcast Talks.
Lewis delivered the talks on BBC radio during World War II, beginning in 1941. He aimed to explain basic Christian beliefs in accessible language to a broad audience, rather than defend one particular denomination.
The material was later issued in book form in stages. The original Broadcast Talks became Christian Behaviour and Beyond Personality, and these sections were eventually combined with a preface into Mere Christianity in 1952.
The title “mere Christianity” refers to the shared core of belief accepted across many historic Christian traditions. It does not mean a vague or minimal version of religion, and it was not the original broadcast title.