Which C.S. Lewis book was adapted from his 1940s BBC radio talks on Christian belief?

Mere Christianity was adapted from C.S. Lewis’s 1940s BBC radio talks on Christian belief. The talks were broadcast during the Second World War and later revised and collected in book form.

Lewis first delivered the broadcasts in 1941, with further series following in 1942 and 1944. He aimed to explain shared Christian ideas in accessible language rather than defend one particular denomination. The book’s title refers to what Lewis regarded as common ground among major Christian traditions.

The final book is divided into sections including “Right and Wrong as a Clue to the Meaning of the Universe,” “What Christians Believe,” “Christian Behaviour,” and “Beyond Personality.” It became one of Lewis’s best-known works of Christian apologetics.

The talks were not simply read aloud from the finished book. Lewis adapted his style for radio, and the published text went through editorial revision. The wartime broadcast setting helped give the work an unusually broad audience beyond academic and church circles.