The New Testament canon that we possess today is due not to the machinations of later church leaders or to the political influence of Constantine but to the fact that these books imposed themselves on the church through their internal qualities. In other words, these books were used the most because they proved themselves to be worthy of that use.

From the very beginning, Christians have plainly affirmed that the Scriptures of the Old and New Testaments are the inspired Word of God. That much is clear. But looming in the background of such an affirmation is a question that won’t seem to go away: How do we know that these books are from God? It’s one thing to say that they are from God; it’s another thing to have a reason for saying it.

Of course, critical scholars have long challenged the Christian view of Scripture at precisely this point. It’s not enough to merely claim that these books are inspired. Christians need to have some way of knowing whether they are inspired. As James Barr liked to point out, “Books do not necessarily say whether they are divinely inspired or not.”

Over the years, Christians have offered a number of answers to this question. Certainly, the Apostolic origins of a book can help identify it as being from God. If a book can be traced to an Apostle, and Apostles are inspired, then we have good reasons to think that the book is from God.

But this is not all that can be said. Christian theologians—especially in the Reformed world—have long argued that there is a more foundational way that we can know that books are from God: the internal qualities of the books themselves.

In other words, they have argued that these books bear certain attributes (Latin indicia) that distinguish them as being from God. They argue that believers hear the voice of their Lord in these particular books. In modern theological language, they believe that the canonical books are self-authenticating. As Jesus said in John 10:27: “My sheep hear my voice, and I know them, and they follow me.”

Anyone familiar with Reformation-era authors will know that this was the core argument given by the likes of John Calvin, William Whitaker, and John Owen in some of the key discussions on Scripture. Moreover, the idea of self-authentication is expressed in the Westminster Confession of Faith, which holds that the Bible does “evidence itself” to be from God by its own internal qualities:

We may be moved and induced by the testimony of the church to a high and reverent esteem of the Holy Scripture. And the heavenliness of the matter, the efficacy of the doctrine, the majesty of the style, the consent of all the parts, the scope of the whole (which is, to give all glory to God), the full discovery it makes of the only way of man’s salvation, the many other incomparable excellencies, and the entire perfection thereof, are arguments whereby it doth abundantly evidence itself to be the Word of God. (1.5)

Beyond this, the concept of a self- authenticating Bible played a central role for later Reformed thinkers, particularly Herman Bavinck, as they sought to explain how we know that books are from God.

But some will wonder, Is this whole idea of a “self-authenticating” Bible just a novel invention of the Reformers? Did they invent the idea just as a tool in their fight against Rome? Not at all. When we look back even in the patristic period, we see that this concept was there from the beginning. Here are a few examples.

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