On the Ebstorf mappa mundi (1235–40 or ca. 1300), where the entire earth is spanned by a gigantic figure of Christ, the shrine of the apostle Thomas appears in India, to record the fact that he brought the Gospel there. Jeffrey Jaynes, professor of church history at the Methodist Theological School in Ohio, discusses this major cartographic document along with several other medieval and early modern world maps that feature the presence of “Christianity beyond Christendom.” To define the boundaries of Christendom, the author refers to the world map produced in 1507 by the German cartographer Martin Waldseemüller, where the corpus Christianum was identified with the area under the ecclesiastical jurisdiction of Rome, and constituted “almost the whole of Europe,” as the mapmaker put it. However, for centuries, stories of ancient Christian communities beyond those boundaries had regularly reached—and been told in—the West. Marginal and isolated religious groups—Copts, Nestorians, and Jacobites, for instance—confessed the Christian faith in the Near and Far East, in Egypt and India, Nubia and Ethiopia, Georgia and Armenia. How were these groups represented on medieval and early modern world maps?

In his comprehensive survey, Jaynes accompanies the reader on a long journey. Once the Roman Empire had become the Christian oikoumene, early medieval maps visualized a global Christianity that privileged a Western, Roman expression of faith despite theological controversies and the expansion of Islam. Later, fully fledged mappae mundi, such as the Hereford and Ebstorf maps, recorded the presence of different Christian communities in Asia and Africa. Later still—from 1300 to 1500—many so-called transitional world maps featured religious differences and conflicts, depicting dispersed Christian traditions differently as travel accounts and missionary reports developed a new understanding of the Christian world, alongside the development of new approaches to mapmaking. In the early fifteenth century, Ptolemy's Geography and its maps were recovered by Western Europe and often Christianized. Interestingly, in a time of universal claims by the Church of Rome, Johann Reger's Registrum in the Ulm Ptolemy (1486) contained several references to Christian traditions scattered in Asia and Africa; distant Christianities also featured in the new global maps and cosmographies produced in the sixteenth century, when the discovery of a New World radically changed the European imago mundi and new horizons attracted new Christian missionary efforts.

In the sixteenth century, the age of the grand atlases, wall maps, and charts, some mapmakers updated the depiction of Christian communities in Asia and Africa, while others ignored religious diversity in order to highlight the worldwide role of the Roman Church. The interest in representing legacies of Christian faith rooted in distant Asia or Africa, however, gradually disappeared from European world maps. A New World had emerged within the Old. Little was left of the notion of a global Christian empire. The diverse early Christian world eventually collapsed into a Western—predominantly Roman Catholic—Christendom. When the Protestant Reformation eventually split Europe into a largely Catholic South and a Protestant North, the notion of a unified Latin Christendom was lost forever. New world maps for a new world order emerged, and Jaynes's survey ends with an examination of the sixteenth-century work by Mercator and Ortelius, neither of whom considered other Christianities in their world maps, apart from a reference to Prester John in Mercator's orbis terrae descriptio.

Christianity beyond Christendom provides new insights and opens routes that can be followed all the way: Why, for instance, did the figure of Prester John in Asia or Africa—unlike other remote Christian presences—survive for so long on modern European maps? Is it not significant that in modern cartography, Christian communities scattered across the world were still represented on regional maps of Asia and Africa—for example, on Ortelius's maps of Persia, Russia, and Tartaria and on his map of Prester John's realm in Africa? Is it really true that by the end of the sixteenth century, the Atlantic world—and no longer Jerusalem or Rome—was at the center of the Christian narrative?

In his search for a global narrative of Christendom, Jaynes has explored several centuries of map history with great accuracy and competence. Not only has he shed new light on ideas circulating in the Christian West about diverse expressions of Christianity further afield, but also he has provided his readers with a masterful, detailed, rigorous, and well-informed historical survey of medieval and early modern Western European world maps contained in a single volume.