The purpose of the Bible was for God to reveal himself and his plan of redemption to us. Everything that we need to know about having a relationship with God is given to us in the Bible. That's why the Bible is so important. To take this thought one step further, we would say that without the Bible, we could not how to have a relationship with God. We would invent our own ideas those ideas would look nothing like what God has actually said. The only place to find the truth about God is in the Bible. People who seek to lead or teach others about God need to base that teaching on the Bible and not on opinion.  Paul told us in Romans 10 that faith comes by hearing and hearing through the word of God.