I was not really sure what I was expecting when I started to read this book; the citation of the US Supreme Court's Obergefell v Hodges decision (576 US ___ [2015]) in the first sentence of the Foreword did not focus expectations significantly. But each page brought its own surprises, and this erudite, well-written and massively researched work was rewarding to read. Anthony Roeber taught most recently (1996–2017) at Penn State University, where he served as department head for ten years; he is now Professor Emeritus of Early Modern History and Religious Studies. He served concurrently as co-director of the Max Kade German–American Research Institute, and co-editor of the Max Kade Book Series at PSU Press. He is also, perhaps most significantly for this work, a priest of the Antiochian Orthodox Christian Archdiocese of North America.

One of the first things which strikes the reader coming from a canon or ecclesiastical law background is how vastly differently law is approached in the Orthodox churches. The first chapter seeks to define, to the extent that they can be defined at all, the main terms of marriage, Church, mystery and oikonomia, and in each instance the point is repeated that the Orthodox and Western Christian (Catholic, Anglican and Protestant) traditions diverge significantly, to the point that similar terms mean vastly different things. For example, ‘mystery’ (in the East) and ‘sacrament’ (in the West) are not equivalent terms, though there are historical periods in which they somewhat approximate to each other; the same is true of oikonomia and equity. It is remarkable, if not altogether surprising, that the extent to which the Catholic and Protestant debates (or conflicts) over the nature of the Church are almost completely absent in Orthodox writing until quite recently, when they appear in the context of discussions of the Eucharist. One surprising connection, of the many portrayed in this book, is between the Mystery of Marriage and the Mysteries of Christian Initiation in the Orthodox tradition. This has echoes in the West as well: while much has been made of Pope Francis’ and Cardinal Kasper's references to oikonomia and akribeia when applied to admission of the divorced and remarried to Holy Communion (they ‘explicitly introduced those terms into the juridical vocabulary of the Catholic Church’ (p 205)), Pope Francis’ suggestion of a ‘catechumenate’ before marriage, although not mentioned in this book, may show a convergence of thought, if not of agreement.

This issue of mixed marriages is carefully chosen as a way of unlocking the astonishing variety of the Eastern and Oriental Orthodox writers, both in the patristic era and in more recent periods. Roeber seeks to untangle the legal, historical, theological, liturgical, sociological and pastoral threads which come together in the quandary of mixed marriages, defined here as the marriage of an Orthodox and a non-Orthodox (although, in some cases, it may also be the marriage between members of two different Orthodox churches). The categories of validity and invalidity are not a major concern of the Orthodox writers, but rather the fact that the two spouses, joined in a mixed marriage, are fundamentally separated by being unable to share in the Eucharist. The thirteenth-century Byzantine canonist Theodore Balsamon is quoted several times as expressing the startling understanding of a ‘hypostatic union’ between the spouses, ‘in varying degrees of iconic similitude to Christ's own relationship to his Church’ (p 231), which manifests ‘one soul in two bodies’ (‘having more or less the same soul, which is perceived in two hypostases’ (pp 67–68)), but who are nonetheless kept from living out that union sacramentally in the Eucharist. The 2016 document on ‘Marriage and its impediments’, preparing for the Great and Holy Council, reiterated Canon 72 of the Council in Trullo (692): ‘marriage between Orthodox and non-Orthodox Christians is forbidden and is not blessed by the Church’. Since oikonomia (‘household management’) can only refer to those who are of the household of faith, that provides no way of resolving the lived experience and increasing tension of mixed marriages throughout the world; the mixed marriages could be blessed ‘out of love’ (dia philanthropian) and ‘tolerated … out of condescension’ (kata sunkatabasin) – two theologically loaded terms – where mercy triumphs over justice. This document, significantly, did not receive approval by the Synod.

This book is also immensely valuable in its review of Orthodox scholarship (the bibliography at the end of the book is almost forty pages long, or 13 per cent of the whole work), not only when addressed to other Orthodox (the debate between the contemporary canonists Ieronymos Kotsonis and Hamilcar Alivisatos is succinctly and well presented), but even more so when that scholarship is in what is not always a very confident exchange with pluralistic, non-Orthodox, society: ‘The distance between the Orthodox understanding of “personhood” and the secular world's obsession with the realization of “self” therefore holds important implications for how the Orthodox witness to and proclaim what they believe takes place in the Mystery of Marriage’ (pp 220–221). That distance is most clearly evident in mixed marriages: at the margins, the frontiers or – as Roeber notes that this space can be named, with a significant change of emphasis – the border.