It is a source of sustenance as well as a deposit of truth. Certainly the Bible has been a primary vehicle of grace and blessing to the saints. From it we have derived the content of faith, receive instruction and are nourished. We might consider the Bible a fundamental sacrament underlying the others. Religious ideas are easily twisted, and ideas about the purpose of Scripture certainly fall into this category.
People have the strangest ideas about what the Scriptures are and how they function.
Others use the Bible as a storehouse of proof texts for constructing their doctrine or projections of future events. Moralists use it to create systems of law, and the hardhearted employ it as a weapon against their enemies. We need to remember that the purpose of the Bible is practical. It was not given as a collection of texts for systematic theology. It nurtures a liberating relationship with God in a rich variety of ways - through narratives, prophecies, wisdom and teachings.