What title did C.S. Lewis give his 1952 book based on wartime radio talks about Christianity?

C.S. Lewis gave his 1952 book based on wartime radio talks the title Mere Christianity.

The book grew out of a series of BBC radio broadcasts Lewis delivered during the Second World War. The talks were intended to explain shared Christian beliefs in language accessible to a broad British audience, rather than to defend one particular denomination.

Lewis later revised and expanded the broadcast material. The resulting book is organized into four sections: “Right and Wrong as a Clue to the Meaning of the Universe,” “What Christians Believe,” “Christian Behaviour,” and “Beyond Personality.”

The title refers to the basic beliefs held in common by many Christian traditions. It is therefore not the name of a new church or denomination. The work became one of Lewis’s most widely read books and helped establish his reputation as a major twentieth-century Christian apologist.