C.S. Lewis’s first BBC wartime broadcast talk aired in 1941.
The BBC invited Lewis to deliver a series of religious talks during the Second World War. The first series, titled Right and Wrong: A Clue to the Meaning of the Universe, began broadcasting in 1941 and addressed ordinary listeners rather than an academic audience.
Further broadcasts followed in 1942 and 1944. Lewis later revised the talks into books, and the material eventually became Mere Christianity, published in consolidated form in 1952.
Mere Christianity was therefore not originally written as one continuous book. Its foundations were radio talks made for wartime Britain, and the title refers to the central beliefs shared across historic Christian traditions.