In short, Bible is the Word of God, the God of Abraham, Issac and Jacob. It is a spiritual book with history, poetry, prophecies, teachings and instructions. But if we look at it outside the spiritual context or if we try to understand it without faith and the revelation of the Holy Spirit, then we will miss the true point of the Book.
In essence, God is revealing Himself to us through His words, the Bible. It is a medium through which He can speak to us. Surly, there are many good principles and moral values you can get from reading the Bible, but its sole purpose is to lead us to God, to Christ Himself, so that we can know Him, which is life eternal.
So if you are reading the Bible, please know there's only one purpose for the Bible to exist, that is so we might get to know God. And I do pray that all of you can read it in such a light and desire to seek Him and know Him, because that is where true freedom lies, where His Spirit it, there is liberty!