What is the title of C.S. Lewis’s book based on his BBC radio broadcasts about Christianity?

C.S. Lewis’s book based on his BBC radio broadcasts about Christianity is Mere Christianity.

The broadcasts were delivered during the Second World War, beginning in 1941, and were intended for a broad British audience rather than only theologians. Lewis discussed moral law, belief, Christian conduct, and the central doctrines shared by major Christian traditions.

The talks were later revised and collected into book form. The title Mere Christianity refers to the basic beliefs Lewis saw as common to historic Christianity, rather than to one denomination. The book is divided into sections including “Right and Wrong as a Clue to the Meaning of the Universe” and “Christian Behaviour.”

Mere Christianity is sometimes mistaken for a transcript of a single broadcast series in its original form. Lewis edited and reorganized the material for publication, so the book is a shaped literary work as well as a record of the radio talks.