When Jesus condemned their traditions, was he condemning everything they came up with during the intertestamental period?
I don’t think so, not based on the writings of St. Paul, since the Pharisees were correct in one area where the Sadducees were wrong, that being belief in the Resurrection of the Dead and the Life of the World to Come.
Also I should say I reject entirely the idea of an Intertestamental period; I believe the corruption our Lord was experiencing in Judaism was a recent phenomenon that began during the life of King Herod the Great, and became worse.
The most recent book in the Bible is the Wisdom of Solomon, which was compiled, from older texts, around 60 BC, and which is truly remarkable, because just 60 years before the Incarnation and 93 years before the Passion of our Lord and the spreading of Christian doctrine, we find these things clearly articulated in this amazing book, which is also one of the most beautiful in the Old Testament, particularly chapter 2, which is a prophecy of the rejection and suffering of our Lord.
I am unable to understand how anyone who has actually read the Wisdom of Solomon, and noted the date at which it was compiled (which is not the same as the date when its contents, which are more ancient, were written, likely by Solomon in at least some cases, or in other cases perhaps attributed to him due to their beauty since the actual author was unknown, a pious custom in that era which also occurred with the early Christian hymns known as the Odes of Solomon, most of which are beautiful but a few of which show evidence of Gnostic corruption…the one thing one must be vigiliant for in examining new documents found from the Patristic era is that they are actually by the Early Church Fathers and not the heretical sects, chiefly the Gnostics, who liked to forge psuedepigrapa with the name of Apostles, who they claimed had passed the material down as a secret tradition, since our Lord would be alleged to have shared this secret knowledge with that one apostle only.
The idea of salvation by secret knowledge is entirely rejected by the Orthodox Church, and indeed some of our concerns about some recent Restorationist churches are due to a seeming neo-Gnosticism in their doctrine. Indeed the 1930s Unitarian catechism implied that American Unitarians were the benefits of some obscure salvific knowledge. This was from when the Unitarians were still nominally, loosely, theoretically Christian, which they are no longer.
I know there is Apostolic tradition. But can it be substantiated that every tradition currently in the Catholic and Orthodox church was established by the Apostles? I think it's alright to have traditions, but I wouldn't call them Scriptural or Apostolic traditions, unless they can absolutely be confirmed as such.
While it is true that not all of Orthodox Tradition can be linked to the practices of the very early church, most can, even the specifics of our Marian doctrine, which at a minimum date from the second century, but it seems unlikely in the paranoid-sensitive church of the second century someone could fabricate the entire contents of the Protoevangelion of James, which is psuedepigraphical but agrees for the most part with our views, without being called out on it by, for example, St. Irenaeus of Lyons. In other cases, it is possible to see the Orthodox Church is the only ancient church that is adhering to various traditions of the Early Church, including, but not limited to, the ancient liturgies of the Alexandrian, Byzantine, Hagiopolitan (Jerusalemite) and Antiohene liturgical rites, fasting on Wednesdays and Fridays, the ordination of bishops by at least three previously ordained bishops, and other requirements of ancient canon law which other churches ignore, the use of the Creed without the Filioque, and so on. In this group I should add that I also include, for purposes of this statement, not just the Eastern and Oriental Orthodox, but also certain Eastern Catholic churches where these things are also the case, if they exist (and evidence indicates they do, despite the OP’s rejection), and also the Church of the East, sometimes incorrectly referred to as the Nestorian Church, which would more accurately be called “the Christian Church in Persia, Mesopotamia, Arabia, and the Far East,” although its membership outside of the Fertile Crescent and the Malabar Coast of India was the victim of a genocide initiated by the Mongol-Turkic Islamic warlord Tamerlane, who distressingly is venerated as a national hero in Uzbekistan.
Why one would venerate the 12th century equivalent of Hitler I cannot fathom, but at least the Uzbeks have not been violent towards those Christians remaining there since the end of the Soviet Union (which consist largely of ethnic Russians and Ukrainians who lived there since the Czarist period in some cases, and Germans forced to settle in Kazakhstan and Uzbekistan by Stalin after WWII).
At any rate, don’t take my word for it; if you read any objective study of Church History, particularly the history of liturgical worship, it will become clear that the Eastern Churches have changed the least overall, in that our Eucharistic liturgies, and the other essential services, are of immense antiquity. Indeed much of what we do know the history of consists of hymns that were composed more recently, largely between the years 400 and 1300, and the enrichment of the liturgies of the Eastern and Oriental Orthodox churches that took place during those years with these additional hymns, and also the various changes; indeed, the changes that were omitted are so well documented, that if we wanted to, we could reconstruct with extreme precision the worship of the Hagia Sophia as it was in antiquity, and indeed the composer, musicologist and director of the amazing choir Capella Romana did just that, in several albums, performing ancient Byzantine church music that was part of the glorious old Cathedral Rite that became disused in Constantinople after the Fourth Crusade and in Thessalonica some time later, by the time the Byzantine Empire was conquered by the Turks, to be sure.
It was the Sabaite-Studite liturgical synthesis as we call it, developed by two ancient monasteries, both of which were lost, Mar Sabbas in the Holy Land and the Studion in Constantinople, that would sustain the parishes during the dark years of Turkish occupation. But at least we still have St. Catharine’s in Sinai, from which the celebrated fourth century Bible manuscript, the Codex Sinaiticus, was stolen by a Belgian adventurer in the 19th century, and sold in sections to the British, Russian and French governments, but recently they returned part of it to the monks, and also where the ancient fifth century icon of Christ Pantocrator, and many other priceless icons, manuscripts and relics are kept. This monastery is in danger due to it being in Sinai, due to terrorist activity and also now the current war in Gaza, although historically it has been protected by the local Bedouins, who it provides with medical care. It is probably worth praying for its monks.
At any rate, my point is the Eastern Churches have more faithfully adhered to the apostolic tradition than any other church; the Roman Catholics and traditional Protestants also keep a lot of it, but there is a problem in their theology, that being the influence of Scholasticism and the overuse of the Latin father St. Augustine and the underuse of the Greek Fathers, Syrian Fathers and other Latin fathers such as St. John Cassian and St. Cyprian of Carthage, and this has created a distinct theology, which one can discern the emergence of in the ninth century, which includes specific innovations like the filioque, the idea of Purgatory as a physical destination analogous to Heaven or Hell, the legalistic idea of indulgences and the treasury of merit, the idea of Papal Supremacy, and so on. The Eastern churches are in a much more pristine state. In terms of how they are governed, the closest thing to them are the Protestant churches of an Episcopal polity, particularly the Anglicans; at different times, parts of Anglicanism have nearly entered into communion with the Orthodox, while other portions did join us and became the Orthodox Western Rite Vicarates (there are two, the Antiochian Western Rite Vicarate, which is the largest, and has services that are derived from Anglican and Roman Catholic usages but corrected to Orthodox theology, and ROCOR’s Western Rite, which focuses on reconstructing the liturgy of England and Western Europe before the takeover of Scholastic Theology and the other changes I mentioned).