It is widely believed that knowledge of history is key to charting a sound course into the future. Yet, this notion is almost always invoked to lament our failure to heed the lessons of the past. In the words of George Bernard Shaw, “we learn from history that we learn nothing from history.” But what exactly does history teach us? In Neighboring Faiths: Christianity, Islam, and Judaism in the Middle Ages and Today, medieval historian David Nirenberg embraces this pressing question. Over the course of nine erudite and stimulating essays—eight of which were published previously, but have here been reframed and revised—he explores how Christians, Muslims, and Jews have understood themselves in relation to one another, while reflecting on the responsibilities of historians to generations past, present, and future.

Neighboring Faiths powerfully challenges two common views. The first is that Christianity, Islam, and Judaism are independent of one another, that they are static, and that one is true and loving while the others are not. The second is that greater knowledge of our neighbors leads to greater tolerance. By applying a variety of analytical lenses to a wide range of encounters between Christians, Muslims, and Jews, Nirenberg demonstrates that Christianity, Islam, and Judaism have long been profoundly interdependent and that they are constantly transforming themselves by thinking about each other—a process he terms “coproduction.” Nirenberg argues further that coproduction involves a dialectic between past and present, as Christians, Muslims, and Jews deploy visions of the past to do work in the present, and as visions of the present shape how we interpret the past (11). The ways in which Christians, Muslims, and Jews have conceived of one another, moreover, are fundamentally ambivalent. In fact, far from cultivating acceptance and understanding, interfaith proximity and familiarity often “heighten the power of polemical forms” (32). What the past offers us, Nirenberg suggests, is not “models to emulate or avoid,” but rather “a stimulus to critical awareness about the workings of our assumptions, hopes, and habits of thought” (3).

Seven of the essays in Neighboring Faiths (chapters 2 to 8) examine the coproduction of religious communities in thirteenth- to sixteenth-century Spain—Nirenberg's area of expertise and the one region of western Europe in which Muslims, Christians, and Jews long coexisted. Each of these essays constitutes a major scholarly contribution in its own right, making the republications most welcome. As a collection, moreover, these studies are particularly thought provoking. Drawing on sources in Latin, Arabic, Hebrew, and Spanish—including law codes, sermons, poems, chronicles, and archival records—they probe the evolution and significance of matters as wide ranging as sexual mores, political ideologies, violence, religious conversion, and language. In addition, they balance judicious consideration of local contexts (the approach of Nirenberg's first book, Communities of Violence: Persecution of Minorities in the Middle Ages [Princeton: Princeton University Press, 1996]) with attention to the enduring power of ideas themselves (the approach of Nirenberg's recent book, Anti-Judaism: The Western Tradition [New York: Norton, 2013]). In so doing, they amply illustrate how the histories of Christian, Muslim, and Jewish identity and difference are inextricably intertwined.

Although not strictly sequential in content, these core chapters form an instructive chronological arc. Chapters 2 and 3 introduce the period prior to the massacres and mass forced conversions of Jews that swept Iberia in 1391. Through an examination of Christian perceptions and portrayals of sexual liaisons between Jewish men and Muslim women, on the one hand, and a Christian king and his (possibly fictive) Jewish mistress, on the other, they consider how Christian ideas about Muslims and Jews shaped Christian religious and political ideologies. They also show that these Christian ideologies, in turn, affected relations between Muslims and Jews, while bolstering and providing grounds on which to criticize new forms of Christian governance. Turning to the violence of 1391, chapter 4—the previously unpublished essay in the collection—examines the effects of the tensions inherent in, and generated by, the special relationship between Jews and royal power, during and immediately following the massacres and forced conversions in Valencia. Chapters 5 to 8 explore the fifteenth- and sixteenth-century consequences of the ways in which mass Jewish conversions to Christianity destabilized traditional categories of religious identity. Tracing shifts in sexual boundaries, Nirenberg argues in chapter 5 that, in the generation after 1391, Christian authorities feared that sex between “old” and “new” Christians involved a blasphemous “sexual proximity to ‘Jewishness’” on account of “incomplete” Jewish conversions (114). Chapter 6 elucidates how, in fifteenth-century Christian literary and political critique, the term “Jew” was “put to new kinds of work” and “filled with new content” (133). The resulting “figures of thought” became key to efforts to exclude “new” Christians from Christian society. In chapter 7, Nirenberg analyzes how, in the face of so much upheaval, both Christians and Jews reimagined their own religious communities and classifications. He argues that the process involved a rereading of each group's own traditions as well as those of its rivals and that it “elevated genealogy to a primary form of communal memory,” giving rise to new forms of historical consciousness and writing (145). Chapter 8 investigates the spread of anxieties about the biological reproduction of religious identity and their relation to the evolving usage of Castilian terms such as raza, casta, and linaje (race, caste, lineage), during the fifteenth and sixteenth centuries. Nirenberg suggests that these early modern “vocabularies of difference” may fruitfully be compared with modern notions of “race” and “racism” (188).

Whereas much of chapters 2 to 8 focuses on how Christians have defined themselves against Jews and Judaism variously understood, chapters 1 and 9 examine how medieval “Christendom” and the contemporary “Christian West” have defined themselves against “Islam.” Broaching the field of medieval Christian-Muslim relations, which is still young, Nirenberg notes that there was much more to Christendom's relation to both Muslims and Islam than enmity. However, he contends, just as Muslims in Christian lands were interested in Christianity primarily for the sake of buttressing their own truth claims, so, too, did Christians study Islam primarily for polemical purposes. In fact, eleventh- and twelfth-century Christian ideas about Islam shaped the formation of the very concept of “Christendom” as an entity united in its mission to defeat Islam. Turning to recent history, in chapter 9, Nirenberg considers how the “Christian West” and “Islam” continue to make sense of the world by defining themselves in relation to one another. Distinguishing between “histories of exclusion,” which focus on supposedly irreconcilable differences and the “clash” between “Islam” and “the West,” and “histories of inclusion,” which focus on shared traditions and synthesis or “alliance,” Nirenberg marshals a dizzying array of evidence. This particularly ambitious chapter considers matters as seemingly far flung as the very brief life of the United Nations Secretariat for the Alliance of Civilizations, Pope Benedict XVI's notorious 2006 “Faith, Reason, and the University” speech, Hegel's attempt at a “total history” of the dialectic of faith and reason, scholarly claims about the “Muslimness” of the origins of Christian vernacular poetry, and the nineteenth- and twentieth-century Jewish and Muslim historiography of medieval Spain. Nirenberg's argument throughout, however, is clear as well as sobering. Narratives of “exclusion” and “inclusion” are “inseparable faces of a debate over Islam that appears in tandem with the idea of Europe itself” (208). Both are fantasies that ignore the gaps between the visions they generate and the complexities of the past and present (193).

Bringing together nine profoundly learned studies that bear on questions of perennial importance, Neighboring Faiths will deeply engage readers interested in interfaith relations, medieval and early modern Spain, and Western history more generally. Advanced students and scholars in particular will value the collection and appreciate its rich endnotes and bibliography as well as its useful index. Although at times challenging to follow, especially in its incorporation of political philosophy and theoretical constructs, Neighboring Faiths is very rewarding to read. Its provocative analysis of the relation of the medieval to the modern, moreover, makes a seminal contribution to the task that lies before all who study history.