Which C.S. Lewis book developed from his BBC radio broadcasts about Christian belief?

Mere Christianity developed from C.S. Lewis’s BBC radio broadcasts about Christian belief.

Lewis delivered the talks during the Second World War, beginning with a series broadcast in 1941. Further broadcasts followed in 1942 and 1944. The talks were later revised and collected into book form, with the title Mere Christianity referring to the shared core of belief among major Christian traditions.

The book is arranged in four parts: “Right and Wrong as a Clue to the Meaning of the Universe,” “What Christians Believe,” “Christian Behaviour,” and “Beyond Personality.” Lewis moves from moral reasoning to Christian doctrine and then to practical consequences.

Mere Christianity is not a denominational catechism and does not attempt to settle every disagreement among Christians. Its purpose is to present what Lewis regarded as basic Christianity. The title can therefore be misunderstood: “mere” means fundamental or common, not trivial or unimportant.