A plumb line measures whether things are vertical, straight, or up to snuff. Amos sees a plumb line measuring the nation of Israel and Israel is not plumb. They have tilted away from the ways of God, justice, and care for those in need. God will not let this stand forever. Either what is out of plumb must be straightened or it will fall. Christ is our plumb line revealing when we are out of sync with God’s reign. By grace, he can bring us back in line with the ways of God.