The Orthodox Church teaches, in short, that there are essentially two written teaching authorities: the Scriptures and oral tradition from the Apostles. According to Saint Peter Mogila’s catechism as approved by the Council of Jassy:
[T]he precepts of the Church are two kinds: one committed in writing, which are contained in the divine books of sacred Scripture and the other delivered by the Apostles by word of mouth. These are the same which the councils and holy fathers did afterwards more at large declare. (p. 14)
What has been given to the Church from “the Apostles; whose traditions, whether by writing, or by word” has been preserved “through the Fathers” and by their writings and interpretations “descended until us.” (Council of Jerusalem 1672, Question 4)
And so, the Church teaches ultimately two things about Apostolic Tradition. First, it is in the Scriptures. This is not debated by anyone. Second, it is preserved in oral traditions that have been both written down and interpreted by saints/fathers in the Church. The second form of tradition, though based upon the “faith which was once for all delivered to the saints” (Jude 1:3) is not frozen in time due to the interpretive/teaching role of the saints/fathers. While Protestants can affirm the former due to 2 Tim 3:15-16, the latter they assert is unscriptural. Ironically, the passage usually cited to confute Protestants on this point, 2 Thes 2:15, is actually in isolation a weak proof text and when understood in its own context does not really prove the Orthodox doctrine before stated.
This being the case, is the Orthodox view of tradition, in effect, not mandated by a Scriptural teaching? No. In fact, the Orthodox teaching on Apostolic Tradition is in plain sight and sadly, due to lazy apologetics, is generally not appreciated. Let’s fix that.
Apostolic Tradition According to Christ. The basis of Apostolic Tradition comes from the Lord Himself, when He states in Luke 18:10, “To you it has been given to know the mysteries of the kingdom of God, but to the rest it is given in parables, that ‘Seeing they may not see, And hearing they may not understand.’” This statement premised the Lord explaining to the disciples the parable of the sower. None of the other parables are explained by the Lord in the Gospels, so the reader (or listener) must assume that the other parables had explanations, but they were not committed to writing. Rather, the Apostles had these.
From the preceding, one may infer that the Apostolic Tradition is not something different than the Scriptures, but rather it is an explanation of some topic covered by the Scriptures. For example, the parable is in the New Testament, but most of their interpretations are not. Now, this may not be exclusively how one may interpret the preceding, but it is a plausible interpretation. That being said, this interpretation is confirmed by further Scriptures on the same topic.
Apostolic Tradition According to the Pastoral Epistles. Perhaps the clearest is 1 Tim 1:3-8. Saint Paul is teaching Timothy in this letter traditions which have not been previously committed to writing. The letter, though it has an individual recipient, was probably written for public circulation (i.e. a “circular epistle”). It was definitely quoted by Saint Ignatius of Antioch and possibly, not long after it being authored, Saint Clement of Rome. It, along with the other “pastoral epistles,” was probably intended to be an “instructions guide” for bishops in the absence of an Apostle.
In any event, Paul literally begins the letter as follows:
As I urged you when I was going into Macedonia, stay at Ephesus that you might command certain men not to teach a different doctrine, and not to pay attention to myths and endless genealogies, which cause disputes, rather than God’s stewardship, which is in faith— but the goal of this command is love, out of a pure heart and a good conscience and sincere faith, from which things some, having missed the mark, have turned away to vain talking, desiring to be teachers of the law, though they understand neither what they say, nor about what they strongly affirm. But we know that the law is good, if a person uses it lawfully. (1 Tim 1:3-8)
From this passage, one can see that there is “a…doctrine” which is acceptable and “a different doctrine.” Whatever these “doctrine[s]” are they pertain to “the Law” as evidenced to Paul’s criticism of those who desire “to be teachers of the Law.” Similar to the Lord’s explanation of parables to the Apostles, here the doctrine pertains to the proper explanation of the Law. Paul presumes that this exists without naming what the facets of correct “doctrine” are. It would be insufficient to pose the entirety of the Scriptures as fulfilling this function, as it would be redundant to interpret the Law with the Law. Paul’s point is that the Law must be interpreted according to “doctrine” (i.e. Apostolic Tradition).
In short, the Apostolic Tradition pertains to correct Scriptural teaching.
While one may rightly argue that the pastoral epistles themselves contain such Apostolic Tradition, to assert that their contents exclusively and exhaustively do so would have been beyond what Saint Paul actually stated. Rather, he simply assumes the recipient would understand correct doctrine without exclusive recourse to the letter. For example, Paul writes to Saint Titus:
I left you in Crete for this reason, that you would set in order the things that were lacking and appoint elders in every city…holding to the faithful word which is according to the teaching, that he may be able to exhort in the sound doctrine, and to convict those who contradict him. (Titus 1:5, 9)
Titus was left in Crete to appoint elders (i.e. Bishops, chorbishops, and priests) who held “to the faithful word” thereby enabling them to “exhort sound doctrine.” Titus may have already been in Crete when he received the letter, which means there would have already been elders instructed in Apostolic Tradition which Titus would have been choosing from. It is also possible that the Epistle to Titus was sent with Titus to Crete and it would have served as his church-planting instructions. Maybe, Titus also would have had a copy of 1 Timothy if it was already authored.
In any event, Paul assumes that these elders would have previously had acquaintance with Apostolic Tradition due to previous evangelization, as Titus is correcting a somewhat chaotic situation, not converting unbelievers and starting new churches out of whole cloth. The meaning of the Greek term used to mean “set in order” has this implication.
Lastly, it is worth noting that Saint Paul explicitly commands Timothy: “the things that you have heard from me among many witnesses, commit these to faithful men who will be able to teach others also.” (2 Tim 2:2) At minimal, this passage shows Paul presumed Timothy would literally teach Apostolic Tradition from himself. Presuming these “many witnesses” are the other Apostles and those who have seen the risen Christ, then this would include an even broader Apostolic witness.
Apostolic Tradition in the Epistle to the Romans. Paul makes an insightful passing statement to the same effect elsewhere. Writing to the Romans, a church he never visited nor instructed at that point in time, he cautioned them to “look out for those who are causing the divisions and occasions of stumbling, contrary to the doctrine which you learned, and turn away from them.” (Rom 16:17) Due to there being no other epistles written to the Romans (and an allegedly chaotic situation as it pertains to receiving information due to the expulsion of Christians at one time according to Acts 18:2 and the local synagogue there being supposedly ignorant of Paul’s doings in Acts 28:21-22), this means that this church was preserving Apostolic Tradition due to previous evangelization.
While certain Protestant sects may infer that before the “closing of the New Testament” God used prophetic gifts to instruct the churches, but once the New Testament occurred this was no longer necessary, the Scriptures nowhere say this. Like the Pentecostals, Orthodox believe that gifts of the Spirit are ongoing (though fathers have admitted they appear far less frequent). Orthodox believe that new doctrines are not made, but rather Apostolic ones “delivered once and for all” (Jude 1:3) are explained. This is the means of preserving or clarifying information that Paul explicitly refers to in Romans.
In Romans, this is why Paul appeals to the doctrine they have already been instructed in. Paul accuses all of those who teach new doctrines of being guilty of sectarianism, something Saint Paul considers damnable (cf Gal 5:19-21).
Conclusion. In review, the Gospels attest to Christ teaching extra-biblical tradition to the Apostles. This tradition was, in effect, the interpretation of these teachings in the parables. One must infer from this that Christ gave the interpretation of many other things, especially the Old Testament (cf Acts 24:32, 45), without these interpretations being committed to writing.
In the writings of Saint Paul, it is simply taken for granted that this “tradition” is a doctrinal understanding that Christians in absence of the Apostles ought to be faithful to. The fact that this idea finds its way in three different letters whose composition are separated by several years shows that it was not some minor idea, but central to Paul’s thought.
If one is to look to the Scriptures for direction on the question of the Orthodox view of Sacred Tradition (as delineated above) versus the Protestant view of Sola Scriptura, it is with the utmost irony that the Orthodox view is explicitly Scriptural unlike the Protestant view. The Apostles did receive a tradition. This tradition is used to understand the Scriptures rightly. The tradition is found specifically among the clergy whose job is to exhort (i.e. teach) “sound doctrine” by “holding to the faithful word [tradition] which is according to the teaching” of the Apostles. (Titus 1:9)
Lastly, this tradition is passed on from Apostle to clergy (1 Tim 1:3), clergy to clergy (“do not rebuke a presbyter, but exhort him,” 1 Tim 5:1, cf 1 Tim 6:2), and clergy to the people (1 Tim 4:6, 11-13, Titus 2:15). Those who teach otherwise are to be “withdrawn” from (i.e. excommunicated, 1 Tim 6:3-5). In so doing, clergy are commanded to preserve this tradition:
O Timothy! Guard what was committed to your trust, avoiding the profane and idle babblings and contradictions of what is falsely called knowledge, by professing it some have strayed concerning the faith. (1 Tim 6:20-21)
And so, the Scriptures explicitly delineate where the tradition originates (Christ’s teaching), who first taught it (the Apostles), and who is expected to faithfully preserve and teach it (the clergy). The preceding should be considered normative, as it is the only teaching on the subject the Scriptures specifically give. In denying this, the Protestant sects deny the explicit witness of the Scriptures themselves.