We are saved by faith, through grace. So, what role does the law serve? From "The Soul Set Free" by Paul Manuel in the Sabbath Recorder, Oct 2006:
When Paul says, “Love is the fulfillment of the law” (Romans 13:10), he does not mean that love is a substitute for obeying the law, as if God replaced the specific precepts with this general principle. Rather, love is the stimulus for obeying the law.
Love motivates us to please God by heeding what God says will please Him, rather than what we think will please Him or, more often, what will please us. Without the anchor of God’s law, love drifts into “situation ethics,” the notion that love—as we understand it—dictates how we should act in any given circumstance. That sounds good until we encounter a situation that comes in conflict with God’s law.
For example, a woman confides in a male coworker that her husband neglects her. He is not abusive, just disinterested. He sits on the couch, night after night, watching TV, and has no desire to spend time with her.
The coworker, who happens to find the woman attractive, is sympathetic to her plight. If he is not to transgress the law’s prohibition against adultery, he must maintain a certain distance in their relationship. Since, in his mind, the law is no longer relevant, he decides to apply Jesus’ admonition—“love your neighbor as yourself”—by giving her the attention and affection her husband is not.
If, in the words of John Lennon, “Love is all you need,” and if love is a substitute for obeying God’s law, there is nothing wrong with this man’s decision. Is that what Paul means when he says, “Love is the fulfillment of the law”?…
It is not. Love is not a substitute for obeying the law; love is a stimulus for obeying the law. It is what motivates us to please God, which we do by obeying God. And we know what God expects—what pleases Him—because He has revealed that in His law.