Genesis 21 recounts Isaac's miraculous birth to parents beyond childbearing years, highlighting the distinction between human effort and divine promise. It contrasts Ishmael, born through human plans, with Isaac, born through God's supernatural intervention. This emphasizes that salvation and blessings come from God's grace, not our efforts. Our true offering to God is faith, which connects us to Him. When we rest in His promises rather than trying to earn His favor, we find joy, as Sarah did with Isaac. The story points to another miracle birth in Bethlehem, showing God's power to do the impossible.