'Unerring' in the Bible

When the natives saw the creature hanging to his hand, they said to one another, "Beyond doubt this man is a murderer, for, though saved from the sea, unerring Justice does not permit him to live."

so that you may learn to recognize and treasure what is excellent [identifying the best, and distinguishing moral differences], and that you may be pure and blameless until the day of Christ [actually living lives that lead others away from sin];