Which C.S. Lewis book presents a Christian apologetic based on wartime radio talks?

Mere Christianity presents C.S. Lewis’s Christian apologetic based on wartime radio talks. The broadcasts were delivered for the BBC between 1941 and 1944 and were later revised and collected as a book.

Lewis was invited by James Welch, the BBC’s director of religious broadcasting, to explain basic Christian beliefs to a broad audience. The talks were designed for listeners living through the Second World War, including people with little formal theological training.

The book is divided into four parts: “Right and Wrong as a Clue to the Meaning of the Universe,” “What Christians Believe,” “Christian Behaviour,” and “Beyond Personality.” Its title refers to core Christianity rather than a particular denomination.

Mere Christianity is sometimes mistaken for The Problem of Pain, another apologetic work by Lewis. The Problem of Pain examines suffering, while Mere Christianity developed from radio talks intended to describe shared Christian beliefs.