Let me put the question another way. Does God need the Bible in order to communicate with his human children? I would agree with Paul when he said, to Timothy, that scripture is useful, or profitable (2 Timothy 3:16). But I would not say that it is essential, for the following reasons.
God was interacting with human beings very effectively long before human beings invented writing. (Let’s be clear on that, very important, point. Human beings invented writing. God did not create human beings with a knowledge of how to write.) Writing, as it developed in Eastern Mediterranean cultures, did not reach the level of complexity which allowed humans to write down stories, histories and laws until about 1500BC (which, interestingly, is the earliest date we have for the life of Moses who is widely believed to have written the first five books of the Bible).
The book of Genesis deals with events that happened before humans invented writing. Genesis was, obviously, written after writing was invented, but the events recorded there occurred before the invention of writing. There is no mention of anyone writing or reading in Genesis. Yet, Genesis makes it clear that God communicated very well with humans including Noah, Abraham and many other people that feature in that book. Did God change when humans invented writing? I think we would all agree that he did not.
Human beings invented writing and the Bible is a product of that invention. If humans had never invented writing, we wouldn’t have any books at all so we wouldn’t have the Bible.
God did not need the Bible to communicate with his children before we invented writing and he doesn’t need it now. So, I believe that the Bible is very useful for knowing God, but not essential. Prayer is essential.
We must not forget that for almost all of history, most people couldn’t read. Even today in countries where education is compulsory there are many people who can’t read. There are also many people who can read but don’t enjoy reading. Is God only interested in those of his children who can read or who like to read? Of course not. For most of the last 1500 years in Europe, and in those countries colonized by Europeans, only the priests and members of the ruling classes were taught to read. Do we find, in our Bibles, an account of God only wanting to interact with priests and nobles? No. We do not. We find an account of God wanting to interact with the poor – the very people who would least likely be able to read.
Jesus is Lord. And Jesus repeatedly encouraged his followers to pray. I’m not saying that we shouldn’t read the Bible. Not at all. (See the articles “I love our Bible” and “What did Jesus say about the Bible?”). But Jesus certainly put his emphasis on the importance of prayer.