Paul uses the story of Hagar and Sarah as an allegory to explain two covenants. Hagar, the slave woman, symbolizes the old covenant given at Mount Sinai, which is associated with the law and leads to bondage. This covenant represents the legalistic approach to righteousness, where adherence to the law is required but ultimately reveals human shortcomings and inability to achieve true righteousness on their own.
In contrast, Sarah, the free woman, represents the new covenant of grace and freedom through faith in Jesus Christ. This new covenant is not about following a set of rules but about embracing the promise of salvation and freedom that comes through faith. Paul uses this allegory to encourage believers to live in the freedom and grace offered by the new covenant, rather than being enslaved by the old law.
This passage emphasizes the transformative power of faith and the liberation it brings, encouraging believers to rely on God's promise rather than their own efforts. It serves as a reminder of the freedom and hope found in the gospel, urging Christians to live as children of the promise, not of the law.