Scripture, being the very word of God, as is confirmed within the word of God and explicitly acknowledged by the Catholic Church, is the sole and sufficient authority in the Christian faith. It is useful for doctrine, reproof, correction, and instruction in righteousness, that the man of God may be complete and thoroughly equipped for every good work. Furthermore, it gives understanding to the simple, enabling those who meditate on it to know more than even their teachers.
But the Catholic Church fancies itself the sole teacher of God's religion. In fact, it is so pompous about this claim that the Council of Trent explicitly forbade people from interpreting the Bible contrary to their interpretations. In session 4, they declared "no one, relying on his own skill, shall,--in matters of faith, and of morals pertaining to the edification of Christian doctrine,--wresting the sacred Scripture to his own senses, presume to interpret the said sacred Scripture contrary to that sense which holy mother Church,--whose it is to judge of the true sense and interpretation of the holy Scriptures,--hath held and doth hold,"
When we do rely on our own skill and wrest the scripture to our own senses (in other words, believe your lying eyes), it becomes swiftly apparent why the Catholic Church has this attitude. The Bible is, self-evidently, not a Catholic book. But is it a Protestant book?
Interestingly, I would say "no". Not because I believe the Catholic Church has any credibility, or that the Bible is somehow too ambiguous to correctly understand, but because I do not give the Catholic Church the credibility of calling myself "Protestant". It is ridiculous to give one denomination so much credibility that we give a whole name to anyone who rejects it. What is the name for a non-Mormon? What is the name for a non-JW? What is the name for a non-Lutheran? I don't belong to any of these denominations, or indeed to any denomination at all, and yet the only denomination I need a name for not being a part of is Catholicism?
So no, I don't believe the Bible is a Protestant book. I believe the Bible existed long before there was a Catholic Church to protest. Furthermore, my theology is not based on rejecting the Catholic Church, but upon the true meaning of scripture. It is actually for this reason that I reject many doctrines considered "Protestant", though ironically I have more respect for these than Catholic doctrines. If I had to choose between, for example, Calvinism and Marian idolatry, I'd get a T.U.L.I.P. tattoo.
Nevertheless, I firmly believe an objective reader of sound mind will absolutely draw some very "Protestant" conclusions. Sola Scriptura is not plucked out of thin air, it comes from many scriptures, most notably 2 Timothy 3:16-17. Sola Fide is not made up, it comes from scriptures like Ephesians 2:8-10. The Priesthood of all believers doesn't come from Luther's mind, it comes from scriptures like 1 Peter 2:4-10.
This reasoning is actually identical to the way we operate when it comes to things on which we agree. Catholics, for example, are notoriously pro-life, fiercely Trinitarian, and firmly opposed to Gnosticism. These positions can all be found in scripture. And not just eisegetically. We don't start with the Trinity and go rooting through scripture looking for verses that may hint at it. No, the Trinity is clear in scripture. If you do not know that God is a Trinity, you either haven't been reading the Bible, or you are so inept at reading that you probably think this article is a crochet pattern for rhinos.
Ironically, Catholics do claim we need them to recognise the Trinity. But unless they're also going to claim no one believed in the Trinity until the Council of Nicaea, and that said council made up the entire doctrine, they really need to drop that argument. At any rate, I've never had a Catholic come up to me and disagree with my arguments defending that on which we already agree.
So why the sudden change when it comes to areas in which we disagree? Why can Catholics afford to let scripture speak when it comes to things like the Trinity, but suddenly they have to claim authority over the scriptures when it comes to their more unique beliefs? The reasoning is obvious: without that authority, no one is going to draw those same conclusions. You won't find the Papacy, Purgatory, indulgences, the Marian dogmas, obligations, Transubstantiation, or a "gospel" of works, in the Bible. In fact, it seems to militate against these ideas.
With enough effort, you can make the Bible say anything you want. Polytheism, Gnosticism, the Prosperity Gospel, you name it, if a heretical view exists, it can be defended with misquoted scripture, especially coupled with claims of authority. But once those claims are removed, these heresies seem unnatural. In fact, they are very forced, stretching the text beyond breaking point.
This would explain why Catholic apologists love to literally break the text. "Baptism now saves you", for example. Even if it wasn't poor practice to rip a single verse out of context, surely it should be considered outright sloppy to turn 34 words (depending on your translation) into 4. But Catholics do it, because although the Bible clearly doesn't include baptism among the criteria for salvation, even giving an example of a man who was saved without baptism, their religion teaches that baptism is a requirement for salvation, not "merely", as the same verse says, "...the answer of a good conscience toward God...". So they have to shoehorn that theology into the Bible somewhere.
But when your theology comes from the Bible, you have no need to try to force it in. Thus, as a so-called "Protestant", the only authority I need to claim is the authority of the book I am practically begging you to read. I don't need to say "only my Church can interpret the Bible for you", which is about the most arrogant thing you can say to a fully literate person. I can simply say "right, read here. What do you think that means?" Or I can quote scripture and show them what it says. I can even quote scripture without telling them I'm quoting scripture and have them interpret it without trying to put a Catholic spin on it, they can just agree or disagree, and then I reveal where it comes from.
And so it's obvious not only who's right, but who knows they're right. If the Catholic Church was the one true Church of Christ, it would be able to show, from His word, that this is the case. Their interpretations would flow naturally from scripture, or at the very least be consistent with it with no extra effort. Instead, there are very few Catholic misquotes of scripture that are even remotely convincing. Thus, it seems obvious that Catholic claims to authority are merely attempts to compensate for the fact that without them, few people would convert to Catholicism, and many Catholics, as they do now, would apostatise. As they should.