Book excerpt: The notion of Christianity as a religion of peace was severely tested during the Middle Ages, when killing in the name of God became a sanctified act. In this book, Tim Rayborn traces the development of the early Crusades, Christian views of war and violence, and its attitudes toward Islam, primarily during the turbulent period of the 11th and 12th centuries (with some attention to earlier centuries). A marked shift in Christian perceptions of its own identity coincided with a considerably more martial and aggressive approach to nonbelievers both inside and outside of Europe. This wide-ranging study includes such topics as the background to the First Crusade, the Knights Templar, Bernard of Clairvaux, the Cistercian Order, the works of Peter the Venerable, apocalyptic hopes and fears, and martyrdom in the context of Christian conflicts with Islam. Focusing on French monastic writings, the book also examines papal documents, Spanish polemics, crusade chronicles, and other works. This is a survey of research on these important subjects, and serves as both a reference work and a point of departure for further study.