Why is the concept of the children of promise important for Christians?

The distinction between the children of the bondwoman (Ishmael) and the children of the free woman (Isaac) is crucial for understanding God's covenant. As noted in Galatians 4:28, we, as believers, are like Isaac — children of promise. This concept emphasizes that salvation and the inheritance of God's kingdom are not based on our works but on God's sovereign grace and His promises. This gives Christians hope, affirming that their identity as heirs is secure in Christ alone, contrasting with the futility of works-based religion.