Sorry for the delay, but we must move soon and have 20 years worth of accumulated collections by God's grace to deal with.
Thanks for the commendation on one aspect, but as for the above, "Protestantism" as typically broadly defined includes those who deny some of the most basic core truths that Catholics and Protestants held in common at the Reformation (a RC write i read today placed it at 80%) and SS type evangelicals have contended for, the deviations from which gave birth to the modern fundamentalist movement opposing them and revisionists (which is very manifest in Roman Catholic scholarship) .
And among SS Christians, which excludes cults which effectively operate under sola ecclesia, as does Rome, there is broad consensus that, as said here , "The sufficiency of Scripture recognizes that we have everything we need for salvation and life in the canonical Word. "Salvation is of the LORD" (Jon. 2:9) .
And as said here
That the teaching of Scripture is sufficiently clear on the main things so as to be able to make ordinary people wise for salvation and to equip for every good work,
and
Scripture is a sufficient and final court of appeal in matters of faith and morals.
This is the critical and primary truth, and in opposition to the church being the supreme authority, while the next statement is where there should be some disagreement, and is not critical as even if it is allowed that one can know some salvific truth apart from hearing the Scriptures, it is the latter that determines if that truth is indeed Truth.
to many modern Protestants Sola Scriptura has come to mean that all knowledge necessary for Salvation is exclusively contained in Scripture If "all knowledge," means no knowledge necessary for salvation, rater than its fulness, is contained outside Scripture, then that is untenable, as Scripture states that the Gentiles,
which have not the law, can do by nature the things contained in the law. (Rm. 2:14)
They thus know they are sinners, which is a necessary salvific truth, and thus they must hope for mercy, which is found in Christ. And which God reveals to the honest seeking sinner, of which Cornelius is an example.
Nor can it be held that only in Scripture is gospel truth necessary for salvation, as souls were saved before Moses and there was Scripture, and before the last book of the canon was penned. But some hold (as with the link above) that "the Word God spoke through apostles and prophets and intended for the direction of his church is now found only in sacred Scripture."
Yet, "found only in sacred Scripture" must be understood as Scripture being the source, not that such is not found in preaching of Scriptural truths, "preaching the word" as the early church corporately did, (Acts 8:4) but opposed to a separate distinct source of revelation.
However, this tends to also exclude revelatory Pentecostal gifts, which i hold as being provided for by Scripture until the perfect revelation of Christ comes, and that the "sola" of SS means that it alone is the assured Word of God and transcendent standard for obedience and testing and establishing truth claims, and that its sufficiency pertains to both materially and formally. This does not exclude that salvific Scriptural truth may be conveyed part from formal knowledge of Scripture, as in a dream to Muslims who might kill any preacher they met, but the veracity of that is subject to proof by the assured word of God.
Now its late and i have lots of packing to do. In addition, Likewise it cannot mean If what is meant that all the contradicted `itself must be explained. is contradicted by
John 20:30-31 30 Now Jesus did many other signs in the presence of the disciples, which are not written in this book; 31 but these are written so that you may believe that Jesus is the Christ, the Son of God, and that by believing you may have life in his name.
2 Timothy 3:14-17 14 But as for you, continue in what you have learned and have firmly believed, knowing from whom you learned it 15 and how from childhood you have been acquainted with the sacred writings, which are able to make you wise for salvation through faith in Christ Jesus. 16 All Scripture is breathed out by God and profitable for teaching, for reproof, for correction, and for training in righteousness, 17 that the man of God may be complete, equipped for every good work.
Scripture contains all that is necessary to bring us to salvation. Jesus said so, John did, and Paul did.
That it's the final authority is a given as it is Truth and as such is reliable to be used as an absolute standard by which to measure any other claims.
It doesn't even have to be stated so explicitly to be recognized. Even in science, there are absolute standards by which other things are measured.