The concept of a “companion” is difficult to define; is it necessary background information or is it supplementary material? Some companions provide a useful introduction to a topic with an overview of the current state of the field. This companion is unsure as to its status. The editor would like it to be a “fellow traveller” (p. xiii) with the reader; I felt little fellowship with the contributors.
The editor contributes two introductory chapters, one on the development of the doctrine of the trinity and another of systematic theology. The paucity of both chapters renders them of little value; his account of the development of the trinity is particularly inadequate.
The next part of the companion is entitled “Retrieving the sources”, which might give the reader some hope that the contributors will consider the revelatory status of the trinity. However, only one chapter is devoted to the New Testament (chapter 3). The analysis given in this chapter seems to amount to “if you already accept the trinity you can read the NT triadically”. This chapter gives no historical explanation for the origins of the trinity, and absolutely no justification for this doctrine. The next two chapters, on the Greek and Latin fathers respectively, are more substantial and give an interesting, if one sided, account of the changing emphases in Christian doctrine. To the credit of the contributor, the chapter on the Greek fathers begins with the (so-called) Apostolic Fathers, such as Clement of Rome and Ignatius – a group of writings often overlooked in accounts of the development of the trinity. Yet it is clear that these contributors are not seeking to describe the development of the trinity but rather to argue that it didn’t develop, there was merely a change in emphasis.
The third part of the companion traces the history of the Trinity both before and after the Reformation. However those familiar with such works as Alan Eyre’s The Protestors will be surprised by the absence of any significant discussion of unitarian movements from this period. Similarly, in part five, where the companion discusses other religions, the absence of any discussion of non-Trinitarian Christians is striking.
In sum, the companion provides some interesting insights into the role of the Trinity in Christian doctrine past and present. Unfortunately the presentation of these insights is too one sided to make this a useful resource.