With Philipp Jakob Spener officiating, Johann Wilhelm and Johanna Eleonora Petersen were married in 1680. Over the following decades they shared life together as influential Lutheran Pietists, even after their spiritual commitments cost Johann Wilhelm his position as superintendent in Lüneburg. Finding a warmer welcome in the territory of Brandenburg-Prussia, the Petersens continued to publish and promote their chiliastic views, maintaining personal connections with contemporaries like Spener, Gottfried Wilhelm Leibniz and William Penn.

This book examines the Petersens’ writings of the 1690s to explore the chiliasm (or millennialism) circulating among a wide variety of Pietists and spiritualists in this period. Johann Wilhelm published over fifty works in that decade, most of which revolved around concepts of universal salvation and the fullness of God's kingdom. For her part, Johanna Eleanora published fifteen pieces on similar themes in those years, which author Elisa Bellucci describes as ‘a significant number for a woman of that time’ (p. 20). By focusing on these sources, Bellucci's study adds insight and nuance to the scholarly categories of ‘churchly pietism’ and ‘radical pietism’, both of which characterise aspects of the Petersens’ faith and writings.

For instance, although Johann Wilhelm lost his church leadership position in Lüneburg for continuing to preach chiliastic views, the content of those sermons as such was not judged to be heretical or outside the bounds of established Lutheranism. Being disciplined for his preaching practice rather than his doctrine was an important distinction to both the Petersens and sympathetic colleagues like Spener. After moving to Brandenburg-Prussia, the Petersens could rightly be considered members in good standing of local Lutheran communities and representatives of a kind of ‘church Pietism’, even as their millennial views put them close to radical Pietists, theosophists and spiritualists who were clearly outside Lutheran Orthodoxy.

As has been true of many who have embraced strong views of the coming reign of Christ, the Petersens emphasised the importance of this teaching because it appears in Scripture. They believed that this biblical topic deserved the serious attention of dedicated Christians. Bellucci also provides important context about why millennial themes might have been socially relevant at the time. For instance, the recent expulsion of Protestants from France, the devastations of the Thirty Years War, and the ongoing divisions between Lutherans, Reformed Protestants and Catholics all gave reasons for pious believers to seek divine solutions to earthly problems and to take comfort in the promise of Christ's imminent return.

Earlier writers like Origen and Joachim di Fiore offered the Petersens historical grounding for teachings about Christ's return and universal salvation, controversial as such past leaders might have been in their own time and beyond. Also, other movements of the period like the Philadelphian Society – named after the sixth and penultimate church addressed in Revelation ii – and increased attention to the Jewish Kabbalah among Christians in the seventeenth century leant international and interfaith energy to the Petersens’ brand of Frankfurt Pietism. Although such sources and conversation partners did little to convince theological detractors of the rightness of their views, the Petersens had intentionally aimed to build such proto-ecumenical and trans-confessional bridges through their eschatological writings, which is an interesting credit to them.

While this study does not aim to convince readers today of the correctness of the Petersens’ teachings about the End Times (views which seem largely unconvincing to this reviewer), the larger goal of reevaluating the period through figures on the fringes of the theological mainstream is very worthwhile. By painting such a thorough picture of this unconventional couple, Bellucci has brought readers into greater familiarity with people and movements who are otherwise easily overlooked or dismissed.

Given the ongoing influence that millennial theologies hold among many people and faith communities in the early twenty-first century, this project also adds valuable perspective to the biblical and contextual sources of such ideas, showing how millennial theology consistently speaks to the fears and longings of generations navigating a perplexing world. As a formal work of historical theology written for specialists in the field, this book enriches scholarly discourse about histories of millennial thinking and seventeenth-century Pietism.