In the first few centuries of Christianity, no one had any idea that there was anything called a "Bible." Indeed, at that time, there was no Bible. That didn't happen until the 3rd or 4th century, depending on how you look at it.
Most early Christians were probably illiterate. Indeed, it is very likely that many of the original Apostles were illiterate. There is even evidence in the New Testament that Peter, Paul, and the other apostles were illiterate. Peter and Paul and the other New Testament writers often seem to be dictating to someone rather than writing for themsleves. All you have to do is read the beginnings of most of the New Testament books to see that.
Yet they all had a host of ideas and assumptions that they obviously drew from.
Until Martin Luther in the 1500s said that the Bible was the wellspring of Christianity, no Christian ever believed such a thing about the Bible. Neither the Roman Catholic nor the Eastern or Oriental Orthodox ever believed such a thing. And they don't believe it still. Neither do most devout Anglican or Lutheran or Calvinist Protestants.
The Bible itself never makes claim to the idea that it is the ultimate Word of God.
So where do modern American Evangelicals get this idea, do you think?