The BBC invited C.S. Lewis to give the wartime talks later adapted into Mere Christianity.
Lewis delivered a series of religious broadcasts for BBC Radio during the Second World War. The first series, titled The Case for Christianity, was broadcast in 1942, followed by Christian Behaviour in 1943 and Beyond Personality in 1944.
The talks were eventually revised and collected as Mere Christianity, first published as a book in 1952. Lewis aimed to explain shared Christian beliefs in accessible language rather than argue for the distinctive doctrines of one denomination.
The broadcasts made Lewis widely known beyond universities and literary circles. The BBC did not originally broadcast a program called Mere Christianity; that name belongs to the later book assembled from the radio talks and revised material.