For 2,000 years the Christian churches have developed, disagreed with each other, and divided into separate and often hostile factions. This book, written by a distinguished Church historian, explores the theological lessons to be learnt from this difficult history. The author identifies a recurring historic tendency to identify the Christian life with one or another specific means to holiness, such as ascetic discipline, martyrdom, or the cult of the Eucharist. He examines how historians of Christianity gradually came to terms with the idea that the Church could change, and even lapse into serious error. He also shows how historical perspective has played a key role in many of the most important theologies of the past 100 years. The book concludes that a living Christianity is never absolutely timeless, and that we can only ever perceive a facet of its total revelation, conditioned as we are by our own historical and cultural context.