In his denial of the deity of Christ, Arius was arguably the most notorious heretic of the early church.
Though Arius’s heretical views were soundly condemned by the Council of Nicaea (in A.D. 325), the controversy he sparked raged for another fifty years throughout the Roman Empire. During those tumultuous decades, the defenders of Trinitarian orthodoxy often found themselves outnumbered and out of favor with the imperial court. Yet they refused to compromise.
Among them, most famously, stood Athanasius of Alexandria—exiled on five different occasions for his unwavering commitment to the truth. He was joined by the Cappadocian Fathers: Basil of Caesarea, Gregory of Nazianzas, and Gregory of Nyssa.
But how did these early Christian leaders know that the doctrine they were defending was, in fact, a truth worth fighting for? How did they know they were right and the Arians were wrong? Was it on the basis of oral tradition, a previous church council, or an edict from the bishop of Rome?
No. They ultimately defended the truth by appealing to the Scriptures.
Gregory of Nyssa makes that point explicit in a letter to Eustathius. The Arians claimed that their tradition (or “custom”) did not allow for the Trinitarian position. Gregory responded with the following:
What then is our reply? We do not think that it is right to make their prevailing custom the law and rule of sound doctrine. For if custom is to avail for proof of soundness, we too, surely, may advance our prevailing custom; and if they reject this, we are surely not bound to follow theirs. Let the inspired Scripture, then, be our umpire, and the vote of truth will surely be given to those whose dogmas are found to agree with the Divine words. (Dogmatic Treatises, Book 12. On the Trinity, To Eustathius.)
When Arian custom ran contrary to Trinitarian custom, to what authority did Gregory appeal? The Scriptures.
As Gregory rightly understood, Scripture is a higher authority than tradition. That is why he appealed to the Word of God as the final arbiter in the debate over Arianism.
In so doing, Gregory provides a vivid illustration of the principle of sola Scriptura, twelve centuries before the Reformation. Of course, Gregory was not the only church father who shared in that conviction.
Though many others could be cited, here is a small sampling from eight church fathers who shared Gregory’s perspective on the authority of Scripture.
1. Irenaeus of Lyons (d. 202)
We have learned from none others the plan of our salvation, than from those through whom the Gospel has come down to us, which they did at one time proclaim in public, and, at a later period, by the will of God, handed down to us in the Scriptures, to be the ground and pillar of our faith. (Against Heresies, 3.1.1)
2. Tertullian of Carthage (c. 160–235) [in defending the truth of the Trinity against the heretic Praxeas:]
It will be your duty, however, to adduce your proofs out of the Scriptures as plainly as we do, when we prove that He made His Word a Son to Himself. . . . All the Scriptures attest the clear existence of, and distinction in (the Persons of) the Trinity, and indeed furnish us with our Rule of faith. (Against Praxeas, 11)
3. Hippolytus (d. 235)
There is, brethren, one God, the knowledge of whom we gain from the Holy Scriptures, and from no other source. For just as a man if he wishes to be skilled in the wisdom of this world will find himself unable to get at it in any other way than by mastering the dogmas of philosophers, so all of us who wish to practice piety will be unable to learn its practice from any quarter than the oracles of God. Whatever things then the Holy Scriptures declare, at these let us look; and whatsoever things they teach these let us learn. (Against Heresies, 9)
4. Dionysius of Alexandria (ca. 265):
We did not evade objections, but we endeavored as far as possible to hold to and confirm the things which lay before us, and if the reason given satisfied us, we were not ashamed to change our opinions and agree with others; but on the contrary, conscientiously and sincerely, and with hearts laid open before God, we accepted whatever was established by the proofs and teachings of the Holy Scriptures. (Cited from Eusebius, Church History, 7.24.7–9)
5. Athanasius of Alexandria (296–373) [After outlining the books of the Bible, Athanasius wrote:]
These are fountains of salvation, that they who thirst may be satisfied with the living words they contain. In these alone is proclaimed the doctrine of godliness. Let no man add to these, neither let him take ought from these. For concerning these the Lord put to shame the Sadducees, and said, ‘Ye do err, not knowing the Scriptures.’ And He reproved the Jews, saying, ‘Search the Scriptures, for these are they that testify of Me.’ (Festal Letter 39, 6–7)
6. Cyril of Jerusalem (315–386) [After defending the doctrine of the Holy Spirit]:
We ought not to deliver even the most casual remark without the Holy Scriptures: nor be drawn aside by mere probabilities and the artifices of argument. Do not then believe me because I tell thee these things, unless thou receive from the Holy Scriptures the proof of what is set forth: for this salvation, which is of our faith, is not by ingenious reasonings, but by proof from the Holy Scriptures...Let us then speak nothing concerning the Holy Ghost but what is written; and if anything be not written, let us not busy ourselves about it. The Holy Ghost Himself spoke the Scriptures; He has also spoken concerning Himself as much as He pleased, or as much as we could receive. Be those things therefore spoken, which He has said; for whatsoever He has not said, we dare not say. (Catechetical Lectures, 4.17ff)
7. John Chrysostom (344–407)
Let us not therefore carry about the notions of the many, but examine into the facts. For how is it not absurd that in respect to money, indeed, we do not trust to others, but refer this to figures and calculation; but in calculating upon facts we are lightly drawn aside by the notions of others; and that too, though we possess an exact balance, and square and rule for all things, the declaration of the divine laws? Wherefore I exhort and entreat you all, disregard what this man and that man thinks about these things, and inquire from the Scriptures all these things; and having learnt what are the true riches, let us pursue after them that we may obtain also the eternal good things; which may we all obtain, through the grace and love towards men of our Lord Jesus Christ, with Whom, to the Father and the Holy Spirit, be glory, might, and honor, now and ever, and world without end. Amen.” (Homily on 2 Corinthians, 13.4)
8. Augustine of Hippo (354–430)
Whereas, therefore, in every question, which relates to life and conduct, not only teaching, but exhortation also is necessary; in order that by teaching we may know what is to be done, and by exhortation may be incited not to think it irksome to do what we already know is to be done; what more can I teach you, than what we read in the Apostle? For holy Scripture establishes a rule to our teaching, that we dare not “be wiser than we ought;” but be wise, as he himself says, “unto soberness, according as unto each God hath allotted the measure of faith.” Be it not therefore for me to teach you any other thing, save to expound to you the words of the Teacher, and to treat of them as the Lord shall have given to me. (The Good of Widowhood, 2)
For the reasonings of any men whatsoever, even though they be [true Christians], and of high reputation, are not to be treated by us in the same way as the canonical Scriptures are treated. We are at liberty, without doing any violence to the respect which these men deserve, to condemn and reject anything in their writings, if perchance we shall find that they have entertained opinions differing from that which others or we ourselves have, by the divine help, discovered to be the truth. I deal thus with the writings of others, and I wish my intelligent readers to deal thus with mine. (Augustine, Letters, 148.15)
Clearly, the doctrine of sola Scriptura was championed by Christian leaders long before the Reformation.
Those interested in studying this topic in more detail will benefit from William Webster's in-depth treatment of this subject, found here.