God intended for the bible to be understood. Sure, there are difficult passages and some places may have more than one meaning or layers of meanings, but one can get the general gist of what the bible is saying.
God is the primary author. So while different authors may have different styles, and may use different ways of expressing themselves, ultimately it is what God intended to be written. While God's intention is in agreement with what the human author was writting, it is possible there is teaching that God intends that was not apparent to the author. While Caiaphas is not an author of scripture an analogy to this concept can be seen with his prophecy:
Then one of them, named Caiaphas, who was high priest that year, spoke up, "You know nothing at all! You do not realize that it is better for you that one man die for the people than that the whole nation perish."This means that we try and understand what the intention of the bible is, not what we get from it. I do think that God can speak into a person's personal circumstances from scripture, but one must be very careful; they need to be certain God has spoken and aware of the specifics of what he has and has not said.
He did not say this on his own, but as high priest that year he prophesied that Jesus would die for the Jewish nation, and not only for that nation but also for the scattered children of God, to bring them together and make them one. (John 11:49-52 ESV)
The bible is inerrant. There is good evidence that this is how Jesus and biblical authors saw scripture.
Jesus replied, "You are in error because you do not know the Scriptures or the power of God. (Matthew 22:29 ESV)
All Scripture is breathed out by God and profitable for teaching, for reproof, for correction, and for training in righteousness,... (2 Timothy 3:16 ESV)Even if one only thinks the New Testament is mildly accurate, in Christ and the Bible, John Wenham has made a good case that Jesus and the disciples saw the Old Testament as inerrant. It is this inerrancy that allows us to get so much from scripture. Because it is true in its entirety we can draw true conclusions from secondary elements in the text; compare Jesus refuting the Sadducees by the tense of a Hebrew verb (Matthew 22:32).
The entirety of scripture gives a coherent worldview. This raises the issue of progressive revelation which I may address at a different time.
There are also other considerations when interpreting scripture such as how did Jesus, the apostles and the authors of the bible interpret scripture.
Now if the entirety of scripture is coherent then we can have a hermeneutic that asks which interpretation does justice to all the passages addressing a topic.
In understanding a particular issue I think every scripture should be addressed. By doing justice to all passages I envisage an interpretation in which every scripture that touches on a particular topic makes sense. Some passages speak to a topic more clearly than others, but it is important to understand what all of the bible has to say about a particular topic. This is, or should be, the goal of systematic theologians. But rather than defining a theology with a few specific verses, it is important to try and review all the relevant verses to come up with an understanding that does justice to them all. Verses do not trump other verses, rather they enhance each other.
Within this framework there are some general rules. Examples include the context of the passage. The specific overrides the general. Lack of exception clauses do not exclude exceptions mentioned elsewhere.
So what is the place of reason in all this. Reason is very important, it is an attribute of God his has implanted in us. It lets us generalise what we know. It allows us to learn from analogies. It helps stop us believing mutually exclusive propositions. But it is also marred. We are made in the image of God, but we are also fallen. That means that while we must use our reason, when our reasoning from scripture leads us to contradict scripture, rather than proposing unlikely interpretations we need to go back to our assumptions and review whether what we have believed about a passage is really so. And looking at all of scripture helps us do this.