How does God's grace distinguish believers?

In Romans 9:6-8, Paul explains that not all who are descended from Israel are true Israel, indicating that God's grace is the means by which believers are distinguished. Those who are called, redeemed, and given faith are considered the true children of God, as seen in Romans 11:26: 'All Israel shall be saved.' This illustrates that it is not by human effort or descent that one is saved, but rather through God's sovereign grace. Understanding this distinction fosters humility and gratitude in believers, reminding them that their faith is a gift from God.