Actually, what made me decide to do this was a reading from two days ago (1.7.4-5), on the authority of scripture. This passage is a real struggle for me. I find Calvin's thoughts both beautiful and terrifying:
Let this point therefore stand: that those whom the Holy Spirit has inwardly taught truly rest upon Scripture, and that Scripture indeed is self-authenticated; hence it is not right to subject it to proof and reasoning. And the certainty it deserves with us, it attains by the testimony of the Spirit. ... Therefore, illumined by his power, we believer neither by our own nor by anyone else's judgment that Scripture is from God; but above human judgment we affirm with utter certainty (just as if we were gazing upon the majesty of God himself) that is has flowed to us from the very mouth of God by the ministry of men.
Whenever, then, the fewness of believers disturbs us, let the converse come to mind, that only those to whom it is given can comprehend the mysteries of God.
Immediately I can hear many of my friends shouting an "amen" to these words, yet in the same instant I can picture many others cringing, or perhaps rolling their eyes.
Calvin's words are worth considering. Personally I would not roll my eyes at them, just as I do not roll my eyes at the claims of Islam or any other religion which claims a sacred text. Do we seriously expect to ascend to heaven with our own minds, to know what God is like through our own finite efforts? If God is there, then surely He has been good enough to somehow communicate to the human race in terms that are clear enough.
On the other hand, it is hard not to cringe, out of a mixture of fear and doubt and frustration. It is not hard to see how Muslims could make the same case for the Koran, or a Mormon for the Book of Mormon. Any religious person could bring forward a profound religious text and defend it as God's own word, and claim that anyone who does not receive it as such has simply not been enlightened by God.
Of course, it would not be fair to say that Calvin doesn't care about reason and proof. He is not saying he would never give rational arguments to confirm the witness of the Holy Spirit that Scripture is God-breathed. But he is subordinating human reason to divine revelation, which on the one hand seems entirely appropriate, given that what is divine is greater than what is human; and yet on the other hand, there is a danger to subordinating reason to revelation.
Simply look at all the different groups of Christians (let alone other religions) and where they come from. At some point Protestants must have so internalized Calvin's principle that they couldn't help but split and split and split. It is easy to justify leaving others behind when you have internal confirmation from the Holy Spirit. The reason others disagree with you is that they have not been enlightened from above.
Rational thought can easily be made into a Tower of Babel by which proud humans assert their self-reliance, but divine revelation can be equally perverted. It can be an impenetrable wall shielding an all too human idea from human criticism. Ironically, it was this very thing that Calvin was trying to destroy--the wall between Catholic dogma and reasonable critique.
I do think it is insightful how Reformed apologists point out that there is nothing higher than God, and therefore it is logically impossible to find any higher standard by which to scrutinize His Word. However, the desire for a rational defense of Scripture's credibility is not necessarily the desire of arrogant man who wishes to put himself above God. It is, at best, the desire for love.
Reason allows us to see beauty where we didn't see it before. A complicated musical piece can be frustrating to people who don't know what they're listening to. Someone with more training can point out all the subtleties that make the piece enjoyable. Reason, at its best, is one person pointing out to another all the patterns that make the world beautiful.
When Scripture is merely asserted as an authority, it is not hard to see why people would think God does not love us. If He truly desires fellowship with us, let Him offer an explanation of Himself. Let Him guide us gently and show us the patterns in His behavior that make Him so truly beautiful.
In historical context, I think I see what Calvin is doing here in the Institutes, moving authority away from Church leadership and locating it in a common document to be read by all. However, I sense a great need to move beyond what he has done, since it leaves so many questions unanswered. Perhaps what I read later in the year will help.
If I were to continue with all my thoughts on this subject, there's no telling how long this would get, so I think I'll have to end here. Calvin's style is very blunt, which makes him fun to read, though I can see why many people take offense at him. Certainly he has made a tremendous historical impact, and for that reason alone it's probably worth taking the time to read his work.