Mere Christianity

Mere Christianity began as a series of radio broadcasts Lewis gave for the BBC between 1941 and 1944. Britain was at war. The talks were practical, unornate, and addressed to people who had no particular reason to believe anything was true. Lewis was not speaking to believers. He was speaking to anyone willing to follow an argument.

The first section, "Right and Wrong as a Clue to the Nature of the Universe", starts not with scripture but with the observation that human beings quarrel. When they quarrel they appeal to a standard both parties are expected to recognise. That standard, Lewis argued, is not something any culture invented. It shows up everywhere, in every culture, in every era. He called it the Natural Law, and he used it as the opening premise of an argument for a moral lawgiver.

From there the book moves through the case for theism, then for Christianity specifically, and then into its most practically influential section: the description of Christian behaviour and the nature of morality. The chapter on pride as the "great sin" has been cited by readers across denominational lines as the most uncomfortable and useful thing they have ever read.

The book was never written as a book. Lewis assembled the radio talks into their final form and added connecting material. The result is unusually readable for apologetics, with the rhythm of spoken argument rather than written theology, and Lewis had a gift for analogy that makes abstract positions feel immediately concrete.

It has been in print continuously since 1952. It has often been described as one of the books that brought many readers to Christian faith in the 20th century. Its influence on sceptical readers is reflected in the many testimonies published about it.