Book excerpt: Christianity is the world’s largest religion, and has had a profound impact on the course of civilization. Introduction to the History of Christianity is a beautifully crafted and clearly written introduction to Christianity over its 2000 year history. The broad underlying theme of the book is the interaction between Christianity and the secular world, exploring how one has shaped and been shaped by the other. The volume does not attempt to cover the whole of Christian history in detail. It focuses on three key chronological periods pivotal in the development of Christianity: Christ and Caesar, Christianity circa 300–500; Expansion and Order, Latin Christendom, circa 1050–1250; and Grace and Authority, Western Christianity, circa 1450–1650, as well as a concluding section on Christianity in the modern world, providing illustrative snapshots of the tradition over the course of its long development. In addition, the volume includes maps, timelines, quotations from primary source material, a glossary, and a further reading section. No staid, laborious introduction to its subject, Introduction to the History of Christianity offers an inviting and informative overview of this rich religious tradition.