Paul uses Abraham's experience to illustrate a profound truth about faith and righteousness. Abraham was considered righteous because of his faith, even before he was circumcised. Circumcision was merely a sign, a seal of the righteousness he already possessed through faith. This means that righteousness is not dependent on following religious rituals or laws but is a gift from God received through faith. Abraham is thus a spiritual ancestor to all who believe, whether they follow Jewish customs or not.
This teaching is revolutionary because it opens the door of faith to everyone, not just those who adhere to specific religious practices. It emphasizes that God's promise and grace are available to all who believe, regardless of their background or religious observance. This inclusivity is a cornerstone of Christian faith, highlighting that salvation and righteousness are based on faith alone. By focusing on faith, Paul underscores the unity of believers and the universal nature of God's promise, making it clear that faith transcends cultural and religious boundaries.