C.S. Lewis’s Mere Christianity first appeared in book form in 1952.
The book developed from radio talks Lewis gave during the Second World War. The talks were broadcast by the BBC between 1941 and 1944 and were intended to explain basic Christian ideas to a general audience rather than to argue for one particular denomination.
Lewis later revised and combined the broadcast material into three parts: “Right and Wrong as a Clue to the Meaning of the Universe,” “What Christians Believe,” and “Christian Behaviour.” The 1952 volume brought that material together under the title Mere Christianity.
The book is often confused with the original wartime broadcasts because the ideas appeared publicly before the complete volume. Its title refers to the shared core of historic Christianity, not to a separate church or denomination.