Who is more humble:
1) The person who insists that he is the arbiter of truth and understanding?
or
2) The person who recognizes that there is a higher power and diligently tries to be acceptable in His sight?
The book you speak of is (in part) a record of eye witness accounts of the exercise of undeniable divine power. This exercise of divine power proves the identity of the individual in question. This identity gives divine weight to His words. Those words are what we try to center our life around.
It is not just "A Book." The fact that you discount it means that you have chosen not to believe it, but it does not make it untrue. You don't like what it says, so you try to make it look unimportant and wrong.