What is the name of C.S. Lewis’s Christian apologetics book based on BBC wartime broadcasts?

Mere Christianity is C.S. Lewis’s Christian apologetics book based on his BBC wartime broadcasts.

Lewis delivered the original radio talks during the Second World War, beginning in 1941. The broadcasts were intended for a general audience rather than for specialists, and they discussed shared Christian beliefs, moral reasoning, and the meaning of Christian faith.

The talks were later revised and collected in book form. Mere Christianity is organized into four parts: “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 common core of belief shared by the major Christian traditions.

The book is sometimes confused with The Problem of Pain, another Lewis work about Christianity, but the two have different origins and subjects. The Problem of Pain appeared in 1940, while Mere Christianity grew from broadcast talks made during wartime Britain.