The following excerpt comes from a summary of chapter one Michael Kruger’s book The Question of Canon. The full summary is written and provided to those who subscribe to Books At a Glance, a time-saving resource that provides you with substantial summaries of new Christian books. See their very affordable pricing here. You get a free 30-day trial to read all the summaries you want and you can cancel at any time before getting charged.


To properly understand the nature of canon, we must first define it. Two competing definitions of canon have arisen in academic circles, while a third one definition may be suggested.

Exclusive Definition

The first might be called the “exclusive” definition. A. C. Sundberg in 1968 proposed that “Scripture” and “canon” are distinguishable, and on this basis we cannot speak of the idea of canon until the fourth century or later. This definition has been supported widely and has become the most prominent definition of canon.


But there are a few concerns with this definition. First, distinguishing between Scripture and canon is difficult—would not Christians have distinguished between Scripture and non-Scripture, and therefore had a working canon based on what the deemed to be Scripture? Second, what does it mean that the canon was “closed” by the fourth century? There has actually never been a time when the boundaries of the New Testament were closed in the way this definition requires. Indeed, the earliest official act of a church to declare a canon (defined in this way) is the Council of Trent in the sixteenth century. Third, nothing happened in the fourth century that made Scriptures more authoritative or “canonical” than they already were in the second to fourth centuries. Other definitions also deserve a voice.

Functional Definition

A second dominant definition is the “functional” definition, laid out first by A. von Harnack and Theodore Zahn and picked up more recently by Brevard Childs. This definition holds that canon encompasses the entire process by which the formation of the church’s sacred writings took place, including the collection and use of Scripture. Thus, there is no real separation between Scripture and canon.

Positively, this definition recognizes that Christians did possess an authoritative corpus of books long before the fourth century. Negatively, though, this definition struggles to account for books that were sacred to some communities but not others (Shepherd of Hermas, Apocalypse of Peter, etc.). More difficult is that this definition fails to account for the ontology of the canon (its “being,” what makes canon “canon”). In fact, both of these definitions define canon in relation to its use by the church so that the church’s reception makes a book canon.

Ontological Definition

A third definition of canon might be the ontological definition, that a book is canonical if it was written by God authoritatively for his church. Thus, books were canonical from the moment they were written, even if they were not recognized as such until the second to fourth centuries. One might object that this is a theological definition, but what precludes us from viewing canon and Scripture in the way Christians have for two millennia? The historical-critical view is just as theological, just from the opposite perspective.

If we take this definition, we might think of canon as involving stages of creation by God, recognition by the church, and consensus regarding specific books by the church. If we consider stages of canon rather than a fixed date for its creation, then all three definitions have a place. The ontological definition relates to the creation of Scripture and canon; the functional definition relates to the church’s recognition of Scripture as canon; the exclusive definition relates to the consensus by the church about specific books that are authoritative.


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