What is the significance of being a child of promise?

In Galatians 4:28, Paul states that believers, like Isaac, are children of promise. This signifies a profound theological truth: believers are included in God's covenant, a relationship established not by human merit but by God’s sovereign grace. This promise connects back to God’s eternal purpose, whereby all who are united to Christ share in the inheritance that is imperishable. It reflects God’s unchanging promise to save His people and assures believers of their eternal security, rooting their identity in Christ rather than in their works or lineage.