The doctrine of sola scriptura is the belief that the Bible is the only infallible authority for the Christian faith. Just to be clear on that definition, let’s emphasize those two words: only and infallible. The doctrine of sola scriptura does not say that Scripture is the only authority; rather, it says that Scripture is the only infallible authority.

This belief is passionately maintained among Protestants and preached with full conviction. What is not maintained—indeed, it is probably not even realized—is that no Protestant really believes it. They believe it in theory, but in practice they deny it.

How do they deny it in practice? They do so by treating their interpretations and theological traditions as though they were infallible, and if you have an infallible authority in addition to the Bible, then the Bible is no longer the only infallible authority. Of course, no Protestant will actually admit that they do this; but the reality is that it does indeed happen. Whenever a Protestant treats their doctrine as though it is above question and incapable of being wrong, they are effectively declaring (though not in so many words) that it is an infallible teaching. They don’t believe their doctrine is possibly right, or mostly right, but that it is above question.

A primary example of this is their view of their canon of Scripture, that is, their official list of books that belong in the Bible. No Protestant would ever dare to suggest that the Epistle to the Hebrews, for example, is not inspired. It’s simply unthinkable. Why is that? They are treating the tradition of the canon as infallible, yet where does the Bible—which they declare is the only infallible authority—say that the Epistle to the Hebrews is inspired? The reality is that the Bible does not make any such claim, so it must be that they accept it as an inspired (infallible) tradition that has its source somewhere outside the Bible.

It is not just with the canon that this happens. Confessional Protestants, such as Lutherans and Reformed, will sometimes rely on the authority of their confessional statements just as much as they rely on the authority of Scripture. Lutherans do this when they subscribe to the “quia” view of the Book of Concord. The Latin word quia means “because,” so the quia view is the belief that the Lutheran confessions are to be subscribed to because they are faithful to the Scriptures. It is very important to note that the quia view does not say that the Lutheran confessions are accepted if they accurately convey what the Bible says; it claims the Lutheran confessions are accepted because they accurately do so. Thus, the Lutheran confessions are assumed to be a completely correct explanation of Biblical truth, without any conditions. What else is that but to treat them as infallible? And when they are regarded that way, they are elevated to the same level as Scripture itself!

Another example of this is the doctrine of Limited Atonement, the idea that Christ died only for the elect and no others, held by Calvinist and Reformed Christians. I mention this particular doctrine because 1) there is no explicit, clear teaching of it in Scripture, and 2) in spite of that, those who hold to it do so unwaveringly, doggedly, and dogmatically. In my experience, some adherents of this doctrine (and I used to be one!) end up falling back on a logical syllogism to defend it rather than citing and exegeting passages of Scripture. Even when Scripture is brought forth in the attempt to substantiate the view, the attempt is inadequate at best. Nevertheless, as I said, the doctrine is embraced doggedly and dogmatically in spite of the lack of Biblical support. Now if an interpretation of Scripture is embraced doggedly and without question, in spite of the scanty Biblical support, isn’t it clear what the real authority is for those who do that? At the end of the day, it is really not sola scriptura that is followed but rather sola interpretatio.

Thus, the claim of sola scriptura that Scripture is the only infallible authority ends up being hollow, for it really isn’t followed consistently. The doctrine is proclaimed, but in practice it is denied.

So in the end, Protestants have their share of theological traditions—whether in the Westminster Confession of Faith, the Book of Concord, or other official statements of faith—that they really do see as being equal in authority to Scripture. Of course, this is denied, but the stark reality is that it truly does happen in practice. And if the adherents of sola scriptura go against it so frequently, one has to wonder if the doctrine is really believed at all.