Johannes Ehmann's Luther, Türken und Islam is an impressive monograph. It brings to completion about a century of research on Martin Luther (1483–1546) and his views on Islam and the Turks. The book begins with an extensive survey of (mostly German) scholarship on the subject, and illustrates how interpretations of the reformer's thought have focused almost exclusively upon the Ottoman military threat of the sixteenth century as the primary impetus behind his numerous remarks on Islam. This has led many to underestimate the theological motives behind, and implications of, his thought. To shed more light on Luther's ‘theology of Islam’, then, Ehmann begins his analysis by turning to the most comprehensive text in the reformer's literary corpus on the subject – the Verlegung des Alcoran of 1542. Seemingly a simple translation of the sixteenth-century edition of Riccoldo da Monte di Croce's (1242–1320) Contra legem Sarracenorum, Ehmann explains how Luther creatively reappropriated the scholastic Latin text into German and refashioned it to serve a broader polemical agenda. The result was a work that not only took aim at Islam by refuting the Qur'ān, but also attacked the ‘internal enemy’ of Christendom – the papacy. Ehmann continues in subsequent parts of the book to show how the theological debates of the Reformation helped to shape this ambitious attack. Beginning with Luther's earliest writings, he illustrates the young reformer's persistent conviction that the threat of Turkish imperialism should be dealt with, primarily, by cleaning up Europe's house. In the 1520s, though, as the Turks made tremendous advances up through Hungary, Luther also had to address the question of whether or not the Turkish armies should be fought physically. Turning immediately to his two-kingdom doctrine, he made a case for a just war against the Turks. This theme, like the call for repentance, runs throughout Luther's writings. Another one that came to dominate much of his thought after the attack on Vienna in 1529 was his eschatological interpretation of the Turkish advance in central Europe. It was this and the conviction that the emerging evangelical Church was surrounded by enemies on every side that led to Luther's polemic of 1542. It also led to his involvement in a project to publish a Latin translation of the Qur'ān in 1543 and the writing of other works that, while not addressing Islam specifically, had a great deal to say about the ‘religion of the Turks’. Ehmann's analysis and virtual catalogue of quotes and whole works significant to the development of Luther's thought on Islam is admirable. It can be a bit cumbersome, and readers would definitely benefit from first examining one of any number of introductions to the history of medieval Christian thought on Islam currently available. But all in all this is an insightful and penetrating analysis of Luther's thought.