What does it mean to be the children of Abraham?

In Romans 4 and Galatians 3, Paul articulates that being a child of Abraham is not determined by physical lineage but by faith. Believers, both Jews and Gentiles, are regarded as children of Abraham and heirs according to the promise of God because they share in the same faith that justified Abraham. This introduces an expansive understanding of God's covenant family, highlighting that all who believe in Christ are encompassed in the spiritual lineage of Abraham, having the same rights and promises as his physical descendants. This fosters unity among believers of all backgrounds in the body of Christ.