There are basically two ways to read the Bible -- as a book of law, or as a book of promise. Our natural religious psychology wants to read the Bible as law: "God is explaining here how I can win his favor." A law-hermeneutic is the pre-understanding we naturally bring to our Bible reading, every page. But in Galatians 3 Paul explains that he reads the Bible as a book of promise, and he wants us to as well. He sees every page of the Bible as gracious promise from God to undeserving sinners. Is there law in the Bible? Yes. But it was "added" (v. 19). Law was inserted after the promises to Abraham were established. It is promise that comes first (Genesis 12), then law comes later (Exodus 20). It is promise, therefore, that defines the all-encompassing framework within which we are to read everything else in the Bible.
You and I can confidently read the Bible with a hermeneutic of promise. Every page, including narrative, law, wisdom, praise, lament, prophecy -- every page, most deeply understood, shines forth as a promise of grace to sinners in Christ.