Good point. These verses strongly suggest that the oral teaching of the apostles carried authority in the early church, which is a considerable challenge to Sola Scriptura.
I just want to add here my personal opinion as to WHY oral teaching carried authority. This ties in with my position defined at post #9. Works like this:
(1) A prophet or apostle needs to know when a given message did indeed come from God. The Spirit solves this by convicting/convincing them, causing them to feel certain it came from God.
(2) When the prophet or apostle relays that same message to an audience, typically the Spirit would convict the audience as well, causing them also to feel certain about it. On these occasions the audience could not ignore the message in good conscience. That's what made it authoritative/obligatory.
Indeed, although its less Sola Scriptura and more Nuda Scriptura, because the Reformers actually did strongly believe in the importance of tradition.
If we put the beliefs of the Lutherans, the high church Anglicans, the traditional Methodists, the Nazarenes, the Moravians circa 1970-2000, the Congregationalists of the early 20th century, the liturgical Presbyterians and Reformed churches such as the Scoto-Catholics and Mercersburg Theologians, and compared them with the Eastern Orthodox, the Oriental Orthodox, the Assyrian Church of the East, and the Roman Catholic Church under Pope Benedict XVI, we would find a remarkable similarity.
And even if we added the congregations in the Southern Baptist Convention which still have traditional worship music, the Evangelical Friends, some of the Mennonites and Anabaptists, and the Christian Church/Disciples of Christ in the 1970s-80s, we would still find a remarkable amount of similarity.
Its when we start plugging in fundamentalist Calvinism, non-denominational Evangelical megachurches, the Pentecostal and Charismatic movement, contemporary worship, the postmodern theology of the “Seven Sisters” - the large American mainline Protestant churches and their counterparts abroad, the Sabbatarian denominations, and several newer denominations, that we would start to see a variance. Note that I am not accusing these churches, some of which operate on a Nuda Scriptura basis and some of which do not, of being heterodox or heretical or not Christian; on the contrary some of them I have a great affection for. I can’t bring myself to dislike the Episcopal Church for example despite my extreme disagreement with its theological trajectory, nor can I bring myself to oppose the absolute pro-life, pro-sexual morality stance of the fundamentalist Calvinist churches like that of John MacArthur, or the lovingkindness of the Sabbatarians.
Where departures from Christianity happen is when people completely discard tradition, including the very basics like the ChristianForums Statement of Faith. Every group I mentioned above follows basic Christian traditions and either accepts the Nicene Creed directly or has a statement of faith or doctrinal basis that is compatible.
Unitarianism initially appeared because of former Puritan Congregationalists, who as Puritans had leaned towards Nuda Scriptura, began critically re-evaluating scripture, and because the doctrine of the Trinity is largely implicit and because the Enlightenment of the time (which I prefer to call the Endarkenment, when we look at the number of heads its philosophical ideology led to being separated from their bodies in Revolutionary France, and the impact this had in terms of inspiring Karl Marx, who inspired the monstrous Vladimir Lenin and his partners in crime Stalin, Beria, Trotsky, Molotov and Kruschev), and Nietschze who inspired Hitler, and the rise of Deism and Atheism) discouraged belief in miracles and promoted a contempt for what Thomas Jefferson called “Priestcraft”, the result was Unitarianism.
Christian Science and the J/Ws claim a more purely Scriptural basis, but rely on weird interpretations which differ from those of actual Christian churches. And both are dangerous by discouraging medical care and prohibiting the receipt of donated blood products, respectively, leading to many deaths.
