What title did C.S. Lewis give his book based on BBC talks broadcast during World War II?

C.S. Lewis gave the title Mere Christianity to his book based on BBC talks broadcast during World War II.

The broadcasts began in 1941, when Britain was at war, and Lewis was asked to explain basic Christian beliefs to a general audience. He delivered further series in 1942 and 1944. The talks were later revised and collected in book form, with the title Mere Christianity referring to the shared core of belief among major Christian traditions.

The book is divided into sections commonly titled “Right and Wrong as a Clue to the Meaning of the Universe,” “What Christians Believe,” and “Christian Behaviour.” Lewis used accessible arguments and everyday examples rather than writing a technical theological treatise.

The work is sometimes confused with The Problem of Pain or The Case for Christianity. The latter was an early printed version of material from the first broadcast series. Mere Christianity is the later, expanded book title associated with the complete project and remains one of Lewis’s most widely read apologetic works.