The biggest divide in Christendom today is not about the primacy of Christ Jesus, or the role of the church in the world.
The biggest divide is what serves as the chief authority for informing us of the Truth of Jesus, the Gospel, the Truth.
The massive divide between the traditional denominations, like Catholic and Orthodox Churches, and the Evangelical or Protestant movements is the primacy of Scripture.
Catholic and Orthodox adherents routinely point to tradition and history as a seminal source of truth and authority for Christianity. They point to the elders, the church fathers, as well as Scripture, and assert that you need to maintain connection with the Church, the authority of the elders, the teachings of the Early Church Fathers in order to understand the Scriptures. They even posit that the Church came before the Bible, and therefore the authority of the Church is greater than Scripture.
However, this thinking is all wrong. This reasoning ignores revelation and truth, and ultimately places man’s efforts above God’s goodness. Morever, the very Church Fathers whom traditional denominations appeal to actually affirm the revelation that Scripture has Supremacy in revealing to us Jesus, The Gospel, and the full Truth of Christianity.
Here’s a great summation, with references and quotes, provided by Bill Worthy:
Clearly, the doctrine of sola Scriptura was championed by Christian leaders long before the Reformation.
ECF on Supremacy of The Scriptures
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.)
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)
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)
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)
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)
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)
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)
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)