Book excerpt: This meticulously researched study is based on a comprehensive reading of all the major Jewish sources from the Geonic period in the ninth century until the dawn of the Haskalah in the late eighteenth century. Its clearly written and carefully documented exposition of the philosophical arguments used by Jews to refute four central doctrines of Christianity (trinity, incarnation, transubstantiation, and virgin birth) makes a major contribution to a relatively neglected area of medieval Jewish intellectual history.