Which C.S. Lewis book collected revised BBC radio talks first broadcast during World War II?

Mere Christianity collected revised BBC radio talks that C.S. Lewis first broadcast during World War II.

Lewis delivered the talks in a series between 1941 and 1944, when Britain was at war. He aimed to explain central Christian ideas in accessible language to a broad radio audience rather than argue for one particular denomination. The broadcasts were later revised and assembled into book form, with the title Mere Christianity.

The book is organized around themes such as morality, Christian belief, and the virtues of faith. Its name refers to what Lewis presented as common or shared Christianity, rather than the distinctive practices of a single church tradition.

A frequent confusion is to identify The Problem of Pain as the radio-talk collection. That earlier book, published in 1940, is a separate work addressing suffering and divine goodness. Mere Christianity grew directly from the wartime broadcast series and became one of Lewis’s most influential nonfiction books.