What book title did C.S. Lewis give his revised BBC talks on Christian belief?

C.S. Lewis gave the revised BBC talks on Christian belief the title Mere Christianity.

The book developed from radio broadcasts Lewis delivered during the Second World War. The talks were intended for a broad audience rather than specialist theologians, and they presented what Lewis called “mere Christianity”: beliefs shared across the major historic Christian traditions.

Lewis revised and combined the broadcasts into a book published in parts between 1952 and 1955. The final work is arranged in four books: “Right and Wrong as a Clue to the Meaning of the Universe,” “What Christians Believe,” “Christian Behaviour,” and “Beyond Personality.”

Mere Christianity is not a denominational manual and does not attempt to settle every difference among churches. Instead, Lewis focuses on arguments about morality, Christian doctrine, and spiritual transformation. It became one of his most widely read works of Christian apologetics.