Which radio-broadcast book by C.S. Lewis was published in collected form in 1952?

Mere Christianity was published in collected form in 1952 after originating as wartime radio broadcasts.

Lewis first delivered the material in a series of BBC radio talks during the Second World War. The broadcasts aired in three main series between 1941 and 1944, and Lewis later revised and combined them into a book. The 1952 volume presents a case for shared Christian beliefs rather than a detailed defense of one denomination.

The title refers to the “mere” or common core of Christianity, not to a church officially called Mere Christianity. Lewis discusses moral law, human behavior, Christian belief, and the theological ideas he considered central. The work became one of his best-known apologetic books.

Readers sometimes identify The Case for Christianity as the original broadcast title or confuse the broadcasts with the later book. The radio talks were issued in stages, while Mere Christianity is the collected book title most commonly cited today.