Which C.S. Lewis book presents material adapted from his BBC radio broadcasts during World War II?

Mere Christianity presents material adapted from C.S. Lewis’s BBC radio broadcasts during World War II.

The broadcasts were delivered between 1941 and 1944 and were intended to explain and defend basic Christian beliefs in language accessible to a general audience. Lewis’s talks became especially well known for their conversational style and their emphasis on ideas shared by the major Christian traditions.

The book was assembled from three broadcast series: The Case for Christianity, Christian Behaviour, and Beyond Personality. The title refers to what Lewis regarded as common or “mere” Christianity rather than to one specific denomination.

Mere Christianity is often grouped with Lewis’s apologetic works The Problem of Pain and Miracles, but it originated specifically in radio talks. The broadcast format shaped its direct tone and short argumentative sections. The work has remained one of Lewis’s most widely read nonfiction books, although it is not a novel and does not belong to the Narnia series.