Joe, I am thinking that perhaps we are asking the wrong question here; maybe that’s why we seem to talk past each other on SS.
Would you agree that the Scriptures contains the truth necessary for salvation through Christ? Do we need more than that for salvation?
Maybe or maybe not the Scriptures contain the truth necessary for salvation. It is a notion one assumes one way or the other and cannot be proven. I think most people have the pious belief that scriptures do contain the truth necessary.
Now, the question, “do we need more than that for salvation” is ambiguous. Does it mean that we need the scriptures only, or the truth only?
'Scripture only, or bible only," and “sufficiency of scripture” are not the same concept.
Because it is never the bible alone. It is always the bible plus something else. For instance, the original inspired autographs are lost. Therefore it is the autographs plus the copyists.
Scripture was written thousands of years ago in languages alien to most people. Therefore it is bible plus the translators.
The translators learned their Greek and Hebrew from teachers and textbooks, so it is bible plus teachers and textbooks.
There are so many human intermediaries between the individual and inspired scripture–all fallible, and all that we have to trust.
Furthermore, few people actually practice bible alone. They rely on a preacher to tell them what the bible says! Why else listen to long sermons on a hard bench? (Of course there are a few who do practice bible alone–these are the ones who derive their own doctrines from the bible and accumulate followers and begin a new denomination.)
And, supposing that the scriptures contain all the truth necessary–does that mean just anyone can read them and get that truth? History and experience show that the answer is no. Hence, again, 'sufficiency of scripture" does not mean 'bible alone."
But, now, assuming the sufficiency of scripture, we have to ask the question: For whom or what is the bible sufficient? Obviously, scripture is not sufficient for just anybody. It would seem the answer is he or what which has the tools and qualifications to ascertain the truths in scripture. Like, there may be gold in the rocks, but it does you no good unless you have a smelter to get the gold out of the rocks!
Where is this smelter to be found?
Well, who or what wrote scripture to begin with? Where did scripture come from? Scripture was written by members of God’s family, His household. Written by members of the community of faith, the assembly of God, the church. Scripture was written by God’s people, to God’s people, for God’s people.
So, the evident conclusion is that scripture is best understood within the context of God’s people!
After all, we all know that scripture verses must be read in context. Which also means that scripture, the bible itself must be read in its proper context! And what else could that proper context be but the Church, God’s assembly, His faith community.
The Church is the proper smelter and the proper home for scripture. It is the Church to whom scripture is sufficient.
From this we conclude that scripture is not meant for individuals to interpret on their own apart from the faith community that gave birth to scripture.
This is my answer to the OP’s question.