For this post, I will comment upon Websters claims, starting with his opening remarks (his words in green, bold and red highlights mine):
The sixteenth century Reformation was responsible for restoring to the Church the principle of sola Scriptura, a principle that had been operative within the Church from the very beginning of the post apostolic age. (From the Article: "What did the Early Church believe about the authority of Scripture? (sola Scriptura)" by William Webster)This very first sentence of his article lays down a very important claim: The "principle" of Sola Scriptura only became "operative" in the "post apostolic age".
Rephrased for even greater emphasis, Webster is saying: Sola Scriptura was not "operative" during the lifetime of the Apostles.
The question arises: Where does the Bible teach this concept, that Sola Scriptura would be "operative" after the Apostolic age?
The answer - to the embarrassment of the Protestant - is "nowhere". So from the very start of Webster's article, he is laying down a foundation not derived from Scripture, meaning it is a foundation derived from men - and such a foundation can never be anything "firm".
In the second paragraph, Webster elaborates on the thought:
Initially the apostles taught orally, but with the close of the apostolic age, all special revelation that God wanted preserved for man was codified in the written Scriptures. Sola Scriptura is the teaching, founded on the Scriptures themselves, that there is only one special revelation from God that man possesses today, the written Scriptures or the Bible.Starting off with the very Biblical notion that "initially" the Apostles taught orally, Webster makes some very serious leaps of logic: Here Webster asserts that by the time the last Apostle died, all revelation God wanted to preserve was written down. Further, he says the teaching of Sola Scriptura is that "there is only one special revelation" we have available "today". To buttress his claim, he plainly says these notions are "founded on the Scriptures themselves."
What the average reader doesn't know is that Webster's own words and arguments ultimately turn around and condemn and self-refute his own position.
Where does the Bible say all information God wanted preserved was at some point, specifically the end of the apostolic age, confined to Scripture? The answer is, again, "nowhere". And where does the Bible say that there will come a time when only Scripture will contain divine revelation? (Nowhere!)
These are two foundational flaws Webster is building from, and they are such because they are not "founded on the Scriptures themselves."
Further, Webster has unwittingly trapped himself by framing his doctrine in an anachronistic fashion. An anachronism is when someone reads something back into a text that was historically impossible at the time. For example, if we found a writing that said, "George Washington spoke with a device that carried his voice long distances," we could not claim this device was a cellphone because cellphones had not been invented yet. So whatever it was, it wasn't a cellphone. In the case of Webster, he cannot point to any given text of Scripture and say, "See this text, the Apostle is teaching the doctrine of Sola Scriptura to these Christians," because Sola Scriptura didn't exist yet - it wasn't operable yet! In other words, not only does Webster not have a Scriptural basis for his claims (as shown earlier), he has also slammed the door on himself in terms of appealing to any Scriptures in the first place!
Consequently the Scriptures are materially sufficient and are by their very nature (as being inspired by God) the ultimate authority for the Church. This means that there is no portion of that revelation which has been preserved in the form of oral tradition independent of Scripture. We do not possess any oral teaching of an Apostle today. Only Scripture therefore records for us the apostolic teaching and the final revelation of God.Just when you thought his unbiblical presuppositions couldn't get any more grand, he adds yet another fatal error. He summarizes his position by saying the Scriptures are "materially sufficient" - as opposed to "formally sufficient." What he doesn't realize is that his grand "conclusion" is self-refuting, because material sufficiency is not equivalent to Sola Scriptura - since material sufficiency can never amount to an "ultimate authority" by definition (see this article for why this is so).
And as noted earlier, for Webster to claim no oral teaching of the Apostles (independent of Scripture) exists today is nowhere taught in the very authority he himself appeals to.
Webster goes onto appeal to this and that Early Church Father as "proof" that Sola Scriptura was the teaching of the Early Church, but after reading his foundational claims, he clearly has lost credibility to proceed. In other words, if what he's espousing is not taught in the Scriptures themselves, appealing to extra-biblical authorities aren't going to change the fact the doctrine is still unbiblical by definition.
It is simply astonishing that an apologist of his caliber would be building his central doctrine from what is nothing short of uninspired traditions of men. If that's the best support Sola Scriptura can find, then all Protestants have an obligation to reject it.