Mikkelsen offers a robust and lavishly illustrated study of Insular and Continental finds from Viking-Age Norway, making this an invaluable volume for anyone interested in ecclesiastical artifacts, the medieval liturgy, or non-Scandinavian influences on Viking-Age material culture. Viking-Age researchers and scholars of Christianization and missionary work more broadly will likewise by interested in Mikkelsen's conclusions that missionary efforts in Norway progressed through three long phases that started well before the Viking Age. Not all readers will be convinced by these arguments, but they will undoubtedly gain new questions about how to interpret ecclesiastical finds in Scandinavia and abroad.

Mikkelsen organizes his work in three parts. Part 1 gathers sources for understanding the spread of Christianity in Norway and introduces three models or phases of missionary activity. Discussion draws on an eclectic mix of sources and regrettably avoids engaging landmark works, including Sæbjørg Walaker Nordeide's Viking Age as a Period of Religious Transformation (Turnhout, Belgium: Brepols, 2011) and Anders Winroth's Conversion of Scandinavia (New Haven, CT: Yale, 2012). Mikkelsen then outlines three models of missionary activity in two short pages focused specifically on developments in Norway. Part 2 is the heart of this work. Three chapters survey Norwegian stone crosses, Insular and Continental metalwork in Norwegian burials, and the earliest evidence for Christian churches and graves. A fourth chapter reappraises these materials regionally. These chapters present a rich inventory of relevant objects, providing museum numbers, catalog text, and color photographs. Part 3 offers synthetic comments, including a section on “How to Trace Missionary Activity in Norway Based on Material Culture” (166–169). Framed as a conclusion, this section in fact outlines the methodology that seems to inform the text. A series of appendices follows, tabulating find locations, catalog numbers, and notes for twenty different types of clerical and secular artifacts. These appendices function as a key that readers can use to explore the Norwegian museum database (https://www.unimus.no/).

Interpretations hinge around Mikkelsen's proposed models that describe a long process of Christianization, challenging earlier views that most Christian artifacts—even artifacts that date from before the Viking Age—arrived as Viking plunder. Mikkelsen seeks instead to identify certain assemblage groups as Christian traces. He urges links between croziers, reliquaries, and manuscript pointers with missionaries; bronze ladles, bronze bowls, hanging bowls, and sometimes buckets with baptism; and stone crosses with the manifestation of Christianity. He argues that the coincidence of certain artifact types in a shared context—such as bronze bowls and a manuscript pointer alongside Tating ware pitchers and funnel beaker glasses in house I:1a, room C, at Borg in Lofoten—provides evidence for a liturgical site. In this case, Mikkelsen's proposal of a possible chapel opposes the excavators’ views, and his detailed discussion offers an important reappraisal of the hall at Borg (103–116). Mikkelsen also scales up his approach to identify settlements, most notably Kaupang (132–139), as probable missionary centers, and even whole regions, such as Selja and Nordfjord in Sogn og Fjordane (now Vestland) (66–68, 169), as places where he believes missionaries first arrived in the 600s. With this chronology in mind, Mikkelsen reappraises subsequent Viking-Age burials at Borre, Gokstad, and Oseberg as signs of resistance to Christian missionary work, perhaps echoing Martin Carver's earlier studies of Sutton Hoo. He advances the argument that Harald Bluetooth eventually reopened these mounds around 960 to mark the final conversion of Vestfold (128–132).

Ultimately, Mikkelsen's three models function as chronological phases. In Model 1, beginning in the 600s, wandering Irish monks known in later Norse sources as papar arrived singly or in small groups seeking eremitic life. These monks brought Christian artifacts and established short-lived communities in Western Norway. In Model 2, beginning in the mid-700s, missionary efforts began in earnest. Mikkelsen contends that these efforts went undocumented but are implied in written sources. He identifies concentrations of Christian artifacts that suggest missionaries with Continental connections were active in Kaupang in Vestfold but met resistance elsewhere. Missionaries with Insular connections meanwhile left diffuse impressions across Western Norway as well as scant traces in the north, just enough for Mikkelsen to suggest early interactions with the Sami. In Model 3, which aligns with traditional narratives drawn from texts, Norwegian kings imposed Christianity in their bid to consolidate power in the late 900s, though Mikkelsen notes that radiocarbon dates indicate some churches and cemeteries might have already been active by the late 800s.

Even readers who remain convinced that Christian artifacts arrived in Viking-Age Norway primarily as plunder will value Mikkelsen's work as an accessible catalogue of finds. Mikkelsen generally allows his objects to speak for themselves while stimulating new thought on processes of Christianization. His interpretative sections, however, are undermined by uncritical treatment of Christianity and paganism as monolithic religions locked in fatal struggle. Some readers will raise eyebrows at references to “pure” pagan graves (137) or “total” Christian societies (152). Others will note apparent misunderstandings about connected regions, such as a description of early Dublin as a Christian community (136), as well as missed opportunities, such as a lack of comparisons between Norwegian stone crosses and contemporary Insular sculpture or Gotlandic stones. The narrow focus on Norway raises important questions about Mikkelsen's argument, since it is not clear whether his approach to Norwegian finds could work for other areas where Christian missionaries were simultaneously active, such as in Frisia or Saxony, or whether a look at these regions would rebut his reasoning. Nonetheless, Mikkelsen's identification of artifact groups with an early Christian presence makes a serious case that undocumented monks and missionaries may have been active in Norway prior to the Viking Age. Mikkelsen thus contributes to a challenging new vision of Christianization in Norway built on a masterful presentation of evidence and an innovative methodology that might be tested for other times and places.