There is an enormous gap between how many academics , on the one hand, and lay people, preachers and teachers at the evangelical Bible colleges, on the other hand, view the Bible.
Academics are aware that the Hebrew Bible as a written collection came together after the exile in Babylon. This leads to a wide-spread assumption that the narratives, poetry, laws and so on were products of the Persian and Greek periods. Many scholars think the seemingly historical accounts of events about the patriarchs, the Egyptian sojourn and exodus, the conquest, the era of judges, and the monarchy were invented. In other words, they are fiction.
The position held in the churches and Bible colleges and promoted through evangelical radio, television and publishing is that Moses wrote the Torah a thousand years before the Persian period and that the events described are literal and historical.
The ideas of many of the academics are corrosive to Jewish and Christian faith. This is the reason for the extreme on the other side. There is the idea of a slippery slope. If you do not hold to the absolute historicity of the events all the way back—if you give an inch to the critics—some think you will end up with a very insecure faith based on invention.
One of the things I note about evangelical culture is stress on writing. You take a written Bible (on paper or, more and more often, on your phone or tablet) to church or study group with you. You get a written outline of the sermon. You are encouraged to take written notes. The sermon is oral but Bible quotes get projected onto the screen.
You could analyze this as a case of Protestantism having arisen in parallel to the invention of the Gutenberg press. Protestants are supposed to read the Bible for themselves. They project this focus on written text all the way back into the Old Testament. It matters a lot to them to take a traditional view of who wrote the text.
I remember a sermon from a couple years ago when the guest preacher laid much emphasis on the notion that Samuel wrote the books of Samuel. This position suffers from the fact that Samuel dies part way through the narrative. Nevertheless, traditional authorship is seen as a guarantee of the truth of the story.
It takes some imagination for us to put ourselves in a world where hardly anybody had access to written texts. Stories were told aloud or often repeated orally in song or chant as part of worship. Someone who was not necessarily the author told the story or led the worship. People may have had no idea and given little importance to who wrote the material.
The idea of David Carr that ancient scribes often wrote texts to support oral performance is important. Writing was not for most people to read. Carr compared it to written music. Few people will sit down and silently read a music score. The purpose of written music is to support those who perform for other people who listen. So with much writing in ancient times.
I suspect that much of the material that went into the collection of writings that Jews assembled after the exile, was of this kind. The pre-exilic prophets like Amos, Hosea, Micah, Isaiah, and Jeremiah spoke in poetry. Scholars speak of scribal schools that recorded the oracles of the prophets. Jeremiah, for instance, had Baruch as a scribe.
However, it seems to me that it would be very hard to speak off the cuff in the kind of poetry they used. Perhaps the oracles were written down beforehand, not just as records of what the prophets had previously said.
Some documents probably existed in royal archives. Books of laws, proverbs, and the exploits of kings were likely of this kind. But much of the material existed for the use of storytellers and liturgists. Some of this may have been archived at shrines.
Much of it may have been used in processions, rather than static worship at a particular place. For instance, it seems that the feast of Tabernacles likely included a procession that started at a tent camp in the Transjordan and crossed the river. The dwelling in tents and crossing the river acted out the drama of the wilderness experience and settlement accompanied by the people chanting parts of the story.
The idea of a book written by Moses does not really fit this setting. One should note that not only does the Torah assume and record the death of Moses it also (1) is written from the perspective of dwellers of the West Bank, which Moses never was, (2) records kings of Edom who lived long after Moses in Genesis 36, (3) contains laws that apply to Israel’s settled life in Canaan, not to nomadic existence in the wilderness, (4) and frequently uses the phrase “until this day” implying a time of writing after the settlement of the land.
However the idea of four documents, J, E, D, and P also puts too much burden on written documents. Law codes, like the Covenant Code in Exodus 20 ff. and the priestly rules of Leviticus, no doubt existed as archived documents. The book discovered in the Temple during Josiah’s reign was probably a copy of an early version of Deuteronomy. But most of the material surely existed in a less fixed form that amounted to strands of tradition, rather then documents.
Some kind of written collection may have been put together in the late monarchy under Hezekiah or Josiah. I think that the final collection of written books by Ezra and others after the exile did not involve fictional invention, rather it was a putting into new form of prophetic, legal and worship material that had long existed.
So I don’t think I stand on a slippery slope. Although the Bible developed in a way that people embedded in a culture that exalts the written word would not have expected, it is still an authoritative tradition that conveys the word of God.