Ira Katznelson and Miri Rubin's collective volume offers a welcome addition to scholarship on religious conversion, a subject that poses distinctive challenges and opportunities for historians. With its ‘centre of gravity’ in medieval and early modern Europe, the volume's ten essays range from late antiquity to the late eighteenth century and from Mesopotamia and Iran to Ethiopia. In a substantive introduction the editors explain their aim to identify a ‘constellation of elements’ that mark particular instances of conversion but also ‘make systematic comparisons possible’ (p. 4). They suggest that the volume makes two contributions. First, it focuses on three subjects not typically covered in depth in case studies of religious conversion: space and time, gender and narratives of identity. Though not evident from the table of contents, these topics provide the organisational structure of the book. Second, the individual essays draw their inspiration from the social sciences, though social scientific concepts and language remain in the background in most of the essays. Katznelson and Rubin also discuss the main subthemes and their function in the volume, engaging with recent secondary literature on each topic.

The first four essays address the conversion of space and time, beginning with Ora Limor's study of the Holy Land as a microcosm for the conversion of space. Tracing conversions and reconversions of Jerusalem – from Judaism to Christianity, from Christianity to Islam, then back to Christianity and again to Islam – Limor shows that ‘space is never ideologically neutral’ (p. 39). Rather space has ‘a symbolic identity, constructed from memories, beliefs, traditions, and rituals’ (p. 59) and is charged with meaning that can be interpreted differently by different groups. In a fascinating essay on religious transformation in the Eastern Mediterranean, Ronnie Ellenblum shows how routine geographic and demographic factors affected Islamisation and Christianisation ‘without personal conversion being involved’ (p. 65). Examining three calamitous climatic events from the mid-tenth to late eleventh century, he argues for the interconnection of hunger, climatic disaster and accelerated Islamisation in a process of ‘demographic conversion’ (p. 74). Stephen Kaplan adds the element of time to the discussion of conversion in his study of fifteenth-century Ethiopia. By endorsing two Sabbaths as the official position of the Church, introducing new holidays, multiplying Marian feasts and upgrading traditional observances like the festival of Mäsqäl, Emperor Zär'a Ya‘əqob attempted to Christianise the calendar – transforming Ethiopian Christianity into ‘a civilization which organized time and dictated the rhythm of believers' lives’ (p. 82). Shifting to Reformation Germany, Bridget Heal analyses conversion within Christianity through the transformation of church space, showing that conversion to Protestantism did not necessitate iconoclasm. In fact ‘surviving medieval images' and the adaptation of traditional iconography might actually ‘facilitate conversion’ (p. 111) as highly ornamental pulpits and altars that expressed evangelical doctrine became markers of Lutheran identity. Focusing respectively on space, demography, time and church architecture, these four essays succeed admirably in demonstrating the editors' contention that ‘the work of conversion was not complete until the environment matched the newly constituted self or group’ (p. 19).

A second cluster of essays treats the theme of gender and conversion. Joshua Levinson examines the sense of self in late antique Judaism and Christianity, specifically how the self receives ‘somatic articulation and representation’ in discourses of conversion (p. 123). He compares two conversion narratives of the penitent prostitute genre, the Christian account of Pelagia and a parallel early rabbinic tale. Despite differences each narrative shows how ‘changing minds changes bodies' and each creates ‘a different sense of self for the conversionary subject’ (p. 149). Yitzhak Hen traces the emergence of a ‘masculine rhetoric of conversion’, developed largely by Christian bishops as they Christianised late Roman civic and martial virtues in letters to barbarian kings. This rhetoric not only shaped notions of masculinity but was crucial to the process of conversion in the gradual passage from pagan antiquity to the Christian Middle Ages. The final essay on gender jumps to eighteenth-century Germany as Rotraud Ries studies cases of Jewish women who applied for conversion to Christianity in the Lutheran city of Brunswick. Examining their social contexts as well as their justifications for conversion, Ries concludes that most applicants came from lower social classes (six of the fourteen were maidservants). And whether or not they expressed the desire to gain salvation, all applicants saw in conversion the chance for autonomy and the potential for change, in short, ‘the choice of a new life’ (p. 183).

The final three chapters focus on narratives of identity. Yosi Yisraeli analyses different interpretations of converso Jewishness through the writings of two fourteenth-century converts to Christianity. Despite radically different interpretations of conversion – one as betrayal and the other as fulfilment of Judaism – both conversos succeeded in accommodating their own Jewishness in their converted selves. At stake, Yisraeli argues, ‘was the range of possible interpretations and the legitimacy of Jewishness in converso religiosity’ (p. 214). Simha Goldin explores Jewish self-definition in the ninth through eleventh century from the perspective of Jewish leaders' attitudes toward those who converted to Christianity. While most Jews regarded converts in a very negative light, as ‘apostates’ who remained suspect even if they returned to Judaism, Rashi and other leaders preferred to view them as ‘forced converts’ and made every effort to facilitate their return to Judaism. The late Michael Heyd analyses ‘double conversion’ within Christianity through three case studies of famous seventeenth- and eighteenth-century intellectuals who converted from Protestantism to Roman Catholicism and back. Sensitive to the complexities of retrospective accounts of conversion, Heyd offers a nuanced analysis of their self-representation showing that one cannot easily separate social from intellectual motivations. He also suggests that their experiences point to a process of secularisation at work in this period.

Although neither the subtitle nor the table of contents points to its distinctive subthemes, Religious conversion is a cohesive volume. One might wish for more attention to conversion within Islam or to the experience of non-elites, but the book as a whole succeeds in identifying important elements for comparison and in presenting new approaches. Readers should not overlook the introduction, which addresses underlying methodological issues, particularly the function of boundaries as zones of differentiation and interaction, which actors may seek to cross. Whether such actors cross from one religion to another or within religious traditions, this volume reminds us that conversion offers an ideal vantage point for studying the mingled identities, multi-layered interactions and complex processes that have shaped human diversity through history.