What book collected C.S. Lewis's BBC radio talks on Christianity?

Mere Christianity collected C.S. Lewis’s BBC radio talks on Christianity.

Lewis delivered the talks during the Second World War, beginning in 1941, when the BBC broadcast them to a wide British audience. He presented arguments and reflections on shared Christian beliefs rather than focusing on the distinctive doctrines of one denomination. The talks were later revised and assembled into book form.

The published work is organized into four parts: “Right and Wrong as a Clue to the Meaning of the Universe,” “What Christians Believe,” “Christian Behaviour,” and “Beyond Personality.” Its title refers to the common core of Christianity that Lewis believed stood behind denominational differences.

Mere Christianity is not the same as The Problem of Pain, which examines suffering, or Miracles, which argues for the possibility of supernatural events. The radio talks made Lewis a nationally recognized Christian public intellectual before the later popularity of his Narnia novels.