C. S. Lewis's Mere Christianity began as a series of BBC radio talks delivered during the Second World War, when Lewis—an Oxford literature professor and former atheist who had become an Anglican in his thirties—was asked to make the case for Christian belief to a war-weary British audience. The book that emerged from those broadcasts is divided into four parts: an argument from conscience to the existence of a moral law and a lawgiver; a sketch of basic Christian doctrines as Lewis takes most denominations to share them; an account of Christian ethics, including chapters on virtues, marriage, forgiveness, and pride; and a final section on the doctrine of the Trinity and the project of remaking human personality through grace. Lewis's deliberate choice was to defend not any particular denomination but the 'mere Christianity' he believed to underlie them all, presented in the conversational, analogical prose he had developed on the radio. The book has remained continuously in print since 1952, been translated into dozens of languages, and become for many readers—Christian, skeptical, or merely curious—the standard popular introduction to Christian belief. It is also a useful window into the mind of one of the twentieth century's most influential apologists, who would go on to write the Narnia chronicles and Surprised by Joy.