Which C.S. Lewis book was adapted from his radio talks about Christian belief?

Mere Christianity was adapted from C.S. Lewis’s radio talks about Christian belief. The talks were broadcast by the BBC during the Second World War, beginning in 1941, and Lewis later revised their text into books.

The broadcasts addressed themes such as morality, human nature, Christian doctrine, and the meaning of faith. Lewis aimed to present what he considered common ground among major Christian traditions rather than defend one denomination’s distinctive practices. The eventual book therefore focuses on shared beliefs, including moral law, repentance, and Christian virtues.

The work appeared in stages. Broadcast material was first published in separate volumes, including Broadcast Talks and Christian Behaviour, before being revised and combined as Mere Christianity in 1952. That publication history can cause confusion with the individual earlier collections.

The title refers to “mere” Christianity as the central beliefs held in common across historic Christian denominations. It is not a claim that all disagreements between churches are unimportant. The book became one of Lewis’s most widely read works of apologetics and remains closely associated with his wartime broadcasting career.