Christians: Why must the Bible be accepted as literal truth?

Even if we ume that the nominal authors of various parts of the Bible (Moses, Matthew, Mark, Luke, John, Paul, Saint John the Divine, I don't know who was supposed to have written the rest of it) actually wrote what it is they were supposed to have written, they were all still human. Yet the Bible says God created the Earth. Should we not, then, read the Earth as the actual word of God? He left the bones of dinosaurs for us to discover so that we would know the truth of evolution. Why then must we accept the word of God filtered through the minds of imperfect humans over the word of God left unchanged in the Earth?