Again, as we visit the subject of tradition and Scripture, seeking to better understand how the two fit together, I turn to Tertullian in his “The Prescription Against Heretics” and find again that his view of tradition to be different than what I understand both the Eastern Orthodox and Roman Catholic churches hold.
“Chapter 21. All Doctrine True Which Comes Through the Church from the Apostles, Who Were Taught by God Through Christ. All Opinion Which Has No Such Divine Origin and Apostolic Tradition to Show, is Ipso Facto False.
From this, therefore, do we draw up our rule. Since the Lord Jesus Christ sent the apostles to preach, (our rule is) that no others ought to be received as preachers than those whom Christ appointed; for “no man knows the Father save the Son, and he to whomsoever the Son will reveal Him.” Matthew 11:27 Nor does the Son seem to have revealed Him to any other than the apostles, whom He sent forth to preach—that, of course, which He revealed to them. Now, what that was which they preached—in other words, what it was which Christ revealed to them—can, as I must here likewise prescribe, properly be proved in no other way than by those very churches which the apostles founded in person, by declaring the gospel to them directly themselves, both vivâ voce, as the phrase is, and subsequently by their epistles. If, then, these things are so, it is in the same degree manifest that all doctrine which agrees with the apostolic churches—those moulds and original sources of the faith must be reckoned for truth, as undoubtedly containing that which the (said) churches received from the apostles, the apostles from Christ, Christ from God. Whereas all doctrine must be prejudged as false which savours of contrariety to the truth of the churches and apostles of Christ and God. It remains, then, that we demonstrate whether this doctrine of ours, of which we have now given the rule, has its origin in the tradition of the apostles, and whether all other doctrines do not ipso factoproceed from falsehood. We hold communion with the apostolic churches because our doctrine is in no respect different from theirs. This is our witness of truth” (emphasis my own)
There is tradition by word of mouth, yes – but notice that Tertullian says, “and subsequently by their epistles.” Does this not mean that those traditions which first were by word of mouth have now been written down? Based on what Tertullian said, if anyone has any doctrine that is different from that which has been written down in Scripture that doctrine is false. How do we know that what we hold to is the truth? If it matches that which has been written.