The BBC broadcast the talks later collected as C.S. Lewis’s Mere Christianity.
Lewis delivered the original radio talks during the Second World War, beginning in 1941. The broadcasts were designed to explain and defend basic Christian beliefs to a general audience rather than to address only theologians or church specialists. Their conversational style helped make Lewis widely known beyond Oxford and the academic world.
The talks were later revised and published in book form. The material appeared in stages under titles including Broadcast Talks and Christian Behaviour before being gathered as Mere Christianity. The finished book presents Lewis’s case for shared Christian doctrines and uses the phrase “mere Christianity” for the core beliefs common to the major historic Christian traditions.
The BBC connection is sometimes overlooked because many readers encounter Mere Christianity only as a printed book. The work’s origins in wartime radio are important: Lewis was speaking to a national audience during a period of crisis, using clear examples and a direct tone suited to broadcasting.