Which C.S. Lewis book was adapted from his BBC radio talks broadcast from 1941 to 1944?

Mere Christianity was adapted from C.S. Lewis’s BBC radio talks broadcast from 1941 to 1944. The talks were later revised and published as a book that presents a broad case for central Christian beliefs.

Lewis did not originally deliver the complete book under one title. The material appeared in stages: The Case for Christianity, Christian Behaviour, and Beyond Personality. These sections were later collected and edited into Mere Christianity, whose title refers to the shared core of belief among historic Christian traditions.

The work begins with the idea of a moral law and develops through arguments about Christian doctrine, virtue, and transformation. It is not a denominational manual and does not attempt to settle every difference among churches. That broad approach helped make it one of Lewis’s best-known works of Christian apologetics.