Before I do that, I must note a couple of problems with the argument(s) you've presented thus far as a whole...
I still don't see how any of this negates the Bible being the final (or primary) authority in the life of the believer.
As I later clarified, my key principle is authoritative conscience and I've challenged several posters to find me even one exception to that principle. Still waiting in vain, as usual. In NO sense is the Bible a higher authority than conscience. It can't be since conscience DICTATED my decision to commit to one book (such as the Bible) over another book (such as the Koran). Clearly conscience is the highest authority, which clearly DOES negate the Sola-Scriptura claim to being the only final authority.
Firstly, I agree that the Holy Spirit brings direct revelation to the believer, but such revelation is brought through a vehicle at least 99 percent of the time.
A vehicle powered ultimately by conscience, in the final analysis.
Romans 10:17 tells us that faith comes from hearing the Word of God (which is referring to the gospel, the message of Jesus, and the Holy Spirit that powerfully convicts through the living Word that comes from the spoken / written word). In other words, the content of the revelation usually comes to a person through various means. No one sits in the bath and suddenly gets all four of those points in their heart. Each point may come gradually, or they may come fairly quickly at a revival meeting or something. But the fact is that there is content in those four points that the conscience itself does not simply conjure up for itself without some sort of external means.
And that content is useless if there is no authoritative basis for accepting it. Conscience is that authority which morally obligates to accept content (or reject it).
All Sola Scriptura is saying is that the purest form of the message is found in the Bible...
Nope it says more than that. It says that Scriptura is the only final authority. Everything must be checked against Scripture, is the claim.
...not that Scripture is the foundation of the church (negating the relevance of you point (1) above). I've never heard anyone ever preach that scripture is the foundation of the Church. I've only ever heard it preached that Christ is - but incidentally, people usually preach that because the Bible says it and God has spoken to them through the words of the Bible in some way.
Ultimately the visible church (in terms of corporate assemblies) is a body of people with shared beliefs. Those who tout exegesis as the foundation of those beliefs thereby IMPLY that Scripture is the foundation of the church. Yes we all agree that Christ wrote the bible and thus ultimately He is in some sense the foundation, but the evangelical church emphasizes a WRITTEN foundation, often to the disparagement of direct revelation. That's an exact reversal of our proper priorities.
(2) and (3) above are equally too simplistic. Conscience is certainly authoritative to a certain degree to an individual believer, but what of the community? Or the Church universal? My conscience has no real authority over you, correct? So what is the authority we can all at least agree on?
While I am more or less a fan of existential philosophy, we can't reduce Christianity to merely existential modes of thought (i.e. the conscience being a final authority). There is far more at stake than just me and my own spiritual walk.
So you really think that God planned to flourish
unity in the church, as a community, by means of exgetical consensus? Based on a text that wasn't even widely circulated until 500 years ago? And subject to all the faillibility of human intepretation? That was His master plan? Just how stupid do you think God is, anyway? Is it any wonder that the denominations disagree on almost everything - EXCEPT THOSE CONCLUSIONS GIVEN BY DIRECT REVELATION DURING CONVERSION VIA THE INWARD WITNESS. For the most part, that's all they agree on!
Mind entertaining a different prospect or picture, just for a moment? How about something biblical, like a church governed by apostles/prophets (1Cor 12:28). Let me explain how it works. It's really quite simple. A man walks up to you and says: At moment I am your leader. Here are the commands of God. Submit to them now.
He's claiming to be a prophet of God. Isn't that how Moses behaved? Paul? Joshua? And what will be your response. Simple. Do you feel 100% certain at that moment? If so, submit.
Notice that this approach, unlike exegesis, affords the potential of perfect unity in the church.
Hmm...turns out that God isn't stupid after all. He actually came up with a potentially more promising plan for unity than you did.