From which medium did C.S. Lewis’s Mere Christianity originally develop?

C.S. Lewis’s Mere Christianity originally developed from BBC radio broadcasts. He delivered the talks during the Second World War, beginning in 1941, and later revised them for publication as books.

The broadcasts presented basic Christian beliefs in language intended for a broad audience rather than for specialists. Lewis spoke about morality, Christian doctrine, and the meaning of conversion. The talks were later collected and reshaped into the sections now known as The Case for Christianity, Christian Behaviour, and Beyond Personality.

The title Mere Christianity was used for the 1952 book, not as the name of the original broadcast series. That difference explains why sources may give several dates or titles when discussing the work. The radio format was central to its original reach and helped make Lewis a familiar public voice in wartime Britain.