If the Bible's purpose is to reveal God, by necessity it is either completely fictional, or inspired by God. The Bible has to be inspired by God because only God can know God. For “God is the source of knowledge about himself, his ways, and his truth. By God alone can God be known. The knowledge of God is revealed by his self-disclosure.” The reason that we can only know God through His revelation is because God is infinite and we are finite. While God is Holy, we are all sinners. This means it is impossible for mankind to reveal God's nature without the work of God moving through them.
All throughout the Bible, it claims that it is the very words of God. In fact, the words "thus says the Lord" appear over 3,000 times throughout the Bible, making it clear that according to the Bible it is inspired by God. "Man does not live by bread alone, but man lives by every word that comes from the mouth of the Lord" (Deut. 8:3) In the New Testament, Jesus declares that the Bible is from God. "If he called them gods to whom the word of God came..." (John 10:34). This means that if the Bible is to be believed, it has to be inspired by God. If not, we must ignore it completely.
This leads us to the question, should we ignore the Bible completely or believe it as the divine inspired word of God? The proof that we should believe in the Word of God is that the Bible demonstrates it's authenticity through fulfilled prophecy. The Bible is a collection of documents that are historically accurate and reflect prophecies that were fulfilled hundreds or thousands of years after they were originally written.