Seeing the Savior in Genesis 21

 The Two Sons

After years of waiting—through doubt, delay, and faithless detours—God fulfilled His promise. Sarah conceived and bore Abraham a son in his old age, at the very time God had appointed. "For Sarah conceived and bore Abraham a son in his old age, at the set time of which God had spoken to him. And Abraham called the name of his son who was born to him—whom Sarah bore to him—Isaac" (Genesis 21:2-3). Isaac means "laughter." What had once seemed impossible was now crying in Sarah's arms. The child of promise had arrived.

Isaac represents something far greater than one family's joy. He is a picture of the new man in Christ—the life that springs forth when a sinner recognizes the sacrificial work of Christ on the cross and confesses Him as Lord and Savior. At that moment of faith, the believer becomes a possessor of new life from God, born not of flesh but of the Spirit.

Yet there was a problem in Abraham's household. Ishmael. He was not the son of promise—he never had been. Now, with Isaac's birth, his true nature was revealed. Genesis 21:9 tells us that Sarah "saw the son of Hagar the Egyptian, whom she had borne to Abraham, scoffing." Ishmael mocked the child of promise. Perhaps he ridiculed Isaac's smallness or weakness. Perhaps he gloated in his own physical superiority, his years of advantage, his position as the firstborn. Whatever form it took, Ishmael persecuted Isaac. The one born according to the flesh despised the one born according to promise.

Isaac's birth did not change Ishmael's nature—it simply exposed what was already there. Though God would bless Ishmael and make him a great nation, he could never be the son of promise. Similarly, no matter how small Isaac appeared, no matter how fiercely Ishmael mocked him, Isaac's position as the heir was secure. Nothing could alter what God had declared.

The parallel for the believer is vital. When God brings forth new life in us through the redemptive work of Christ, that new man is entirely distinct from the old. The old man does not get reformed or improved. He remains a man of the flesh, seeking only after self. That is his nature, and it continues to be so even after we are born again. The flesh and the Spirit war against each other, just as Ishmael warred against Isaac.

What, then, is the solution? We might think we should educate the old man, refine him, teach him better habits. But Scripture offers no such remedy. Sarah's words to Abraham were clear and uncompromising: "Cast out this bondwoman and her son, for the son of this bondwoman shall not be heir with my son, namely with Isaac" (Genesis 21:10). Colossians 3:9 echoes this truth: "You have put off the old man with his deeds." Not improved. Not rehabilitated. Put off.

The old nature must be cast out, reckoned dead, given no quarter. In doing so, there remains nothing for us to glory in ourselves. We cannot boast of our transformation, our improvement, our progress. Only God receives the glory, and He deserves all of it.

Yet we must be honest: the old man clings to us in this life. Like Ishmael, he mocks and persecutes. He causes us to stumble, to fall, to feel defeated. But here is our assurance—our failures do not change our position. Like Isaac, we are children of promise. Our standing does not rest on our strength but on God's decree. He who began the good work will complete it.

When we come before Him at His table, let us remember this truth. He is the Blesser and we are the blessed. He is the Giver and we are the receivers. All glory belongs to Him alone.