Before I try to answer that question directly, let me make a distinction that is important at the outset. There's a difference between objective proof and the persuasion or conviction that follows. John Calvin argued that the Bible carries both persuasion and conviction in terms of its internal testimony—the marks of truth that could be found just by an examination of the book itself—as well as external evidences that would corroborate that substantial evidence to give solid proof for its being the Word of God.
Yet the last thing people would want is a book telling them they are in desperate need of repentance and of a changed life and of bowing in humility before Christ. We don't want that book to be the truth. Calvin claimed that there is a tremendous bias and prejudice built into the human heart that only the influence of God the Holy Spirit can overcome. Calvin distinguished between what he called the undicia—those objective evidences for the trustworthiness of Scripture—and what he called the internal testimony of the Holy Spirit, which is necessary to cause us to surrender to the evidence and acknowledge that it is the Word of God.
But I think this is a critical issue upon which so much of the Christian faith depends. The Bible makes the claim that it is the unvarnished Word of God, that it is the truth of God, that it comes from him. God is its ultimate author and source, though indeed he used human authors to communicate that message.
In speaking with people about this, we have to go through the laborious process of showing first of all that the Bible as a collection of historical documents is basically reliable. The same tests that we would apply to Herodotus or Suetonius or any other ancient historian would have to be applied to the biblical records. The Christian should not be afraid to apply those kinds of historical standards of credibility to the Scriptures, because they have withstood a tremendous amount of criticism from that standpoint, and their credibility remains intact. On the basis of that, we come to an idea. If the book is basically reliable, it doesn't have to be inerrent or infallible; it gives us a basically reliable portrait of Jesus of Nazareth and what he taught.
We move from there in linear fashion. If we can on the basis of general reliability come to the conclusion that Jesus Christ did the things that history claims he did, it would indicate that Jesus is more than an ordinary human being and that his testimony would be compelling. I would move first to a study of the person of Jesus and then ask the question, what did Jesus teach about Scripture? For me, in the final analysis, our doctrine of Scripture is drawn from the teaching of Jesus and from our understanding of who he is.