Genesis 17-21

III. The gift of a son a demonstration of God’s mercy

Soon after this, Abraham journeyed to the country of the Philistines near Gerar after having spent some time in the land between Kadesh and Shur.

Gerar was in the land of Canaan to the south and west and was ruled by a man whose name was Abimelech. This Abimelech was a God-fearing man preserving a remnant of the true worship of Jehovah in Canaan. There were these few remnants for a long time after the flood where the worship of God was kept alive for some time. Cf. e.g. Melchizedek. But Abraham was afraid in this strange land and therefore promoted the lie that Sarah was his sister. This seems to have been a common policy with Abraham for he did this same thing in Egypt and he tells Abimelech, “And it came to pass, when God caused me to wander from my father’s house, that I said unto her, This is thy kindness which thou shalt show unto me; at every place whither we shall come, say of me, He is my brother.” vs. 13.

Yet Abraham sinned in doing this. He sinned because he failed to trust in God that God would care for him even when he was among enemies. He sinned because, while it was true that Sarah was his half sister (vs. 12), nevertheless, the intent was to leave the impression that Sarah was not his wife. But the greatest part of the sin was that he was willing (which is hard for us to understand) to let Sarah become the wife of another to protect himself. Yet Sarah was, according to God’s Word, the mother of Isaac and of Christ. If she had married another and left the home of Abraham, the promised seed could never be born. This sin of Abraham shows a most remarkable callousness with respect to the promise and an astonishing disregard for the importance of Sarah’s place in the line of the covenant. Abraham by this sin forfeited all right to God’s promise. And yet, how often to not we do the same. No doubt the frailties of the ancient patriarchs are mentioned in Scripture in order that we may know that they were men like us. For if they were men like us, then the faith which God gave them by which they performed such mighty deeds is a faith which God also gives to us. We are so inclined to think that they are too great for us to emulate. But God’s gift of faith is as great in us as it was in them, for they were as weak by nature as we are.

But this was also a sin for Abimelech. It is true that he took Sarah out of innocence and in the integrity of his heart. God also recognizes this. Whether he was attracted by Sarah’s beauty which remained even when she was an old lady of ninety, or whether he took Sarah as the first step in concluding a treaty with Abraham is impossible to determine. But he also sinned. If he had married Sarah, he would have been guilty of taking another man’s wife, and this was his intent. He may not have known that Sarah was Abraham’s wife, but he should have made it a point of finding out. The strangeness of Abraham having an old lady of 90 in his tent who was supposedly only his sister was point enough to make Abimelech investigate if he had wanted to. Therefore, the Lord also punished the house of Abimelech by some sickness which made conception and childbirth impossible for anyone—a sickness which could only be cured by the intercession of Abraham. And therefore God threatens the whole house of Abimelech with death if he did not immediately restore Sarah to her husband.

This Abimelech hastened to do while, at the same time rebuking Abraham for his deception—a rebuke which Abraham deserved. To Abraham however, he gave gifts and especially 1000 pieces of silver so that Sarah would not be shamed in the eyes of others. For by this gift, Abimelech showed that he had respect for Sarah and justified her conduct. (Such is evidently the meaning of vs. 16, for the latter part of the verse could better read, “Thus he justified her.”)

The whole event is a most remarkable demonstration of God’s mercy. By striking the house of Abimelech with illness, God prevented this mother of Christ from becoming Abimelech’s wife. By a dream God revealed Abimelech’s sin to him and used this as a means to restore Sarah to Abraham. And all of it showed that Abraham was not at all deserving of a son, nor of the promise of God’s covenant. But God is merciful to His people and gives His promise not on the basis of their own merits, but out of the infinite fountain of His own sovereign grace.

IV. The fulfillment of the promise

At last the time came when the promise was fulfilled. At the time appointed by God Himself, Abraham and Sarah became the parents of a son. Abraham was 100 years old; Sarah was 90. From every human point of view the birth of Isaac was out of the question. God had seemingly waited too long; Abraham and Sarah were too old.

But this was exactly as God intended, for the birth of Isaac was, in its miraculous nature, a picture of the birth of Christ. Isaac was not born by the will of man nor by the power of the parents who produced him, but by a miracle—a wonder of grace. And so it was with the birth of Christ. He too was not born by the will of man. For it was impossible for man ever to bring forth the Christ. The royal line of David ended in the virgin Mary. But how could men bring forth Him Who is both God and man? So Isaac typified the miraculous birth of the true Seed of Abraham.

Yet at the same time, this birth of Isaac is a picture of the spiritual rebirth of all the elect people of God—the true seed of Abraham. For they, too, are not born as children of God by the will of man and the natural process of conception and childbirth (Cf. John 1:13). They too are born by a wonder of grace, by a miracle as wonderful as creation, by the power of regeneration by which the life of Christ is given to them. Abraham and Sarah had to learn that they could never bring forth the seed of the covenant. This required a work of God. But is not this always true of the seed of the covenant? Cf. Gal. 4:22-28.

The child was named “Isaac”. Isaac means “laughter”. Once Abraham and Sarah had laughed in unbelief; but now, with the birth of their child, their laughter became the rejoicing of thankfulness in which all the saints participate as they contemplate this wonder of grace. Thus Sarah also prophesies, “All that hear me shall laugh with me.” vs. 6.

But trouble soon arose in the home of Abraham and Sarah. This trouble was, in a way, the consequence of Abraham’s own foolishness when he married Hagar in an attempt to produce the promised seed. For Ishmael, the son of Abraham and Hagar began to mock Isaac at the feast that Abraham had prepared at Isaac’s weaning. This was a terrible sin. No doubt Ishmael taunted Isaac with the claim that he and not Isaac was the firstborn and therefore, the heir of Abraham’s possessions and the birthright blessing. He jeered at the promise of God fulfilled in Isaac and sneeringly contradicted the wonderful things God has said of this seed of Abraham. Paul tells us in Galatians that Ishmael “persecuted” Isaac. Gal. 4:29.

Sarah insisted that Ishmael had to be cast out, for she saw the presence of Ishmael as a threat to Isaac who was divinely destined to be the heir of the promise. This was not a cold-hearted, selfish and petty wish on Sarah’s part, but a profound understanding of the truth, “In Isaac shall thy seed be called.” Although Abraham was naturally reluctant to do this, for Ishmael was his own flesh and blood, he obeyed the Lord when God told him that Sarah was correct.

But this too is significant, for Paul later refers to this same event in Galatians 4:29, 30. Ishmael was the reprobate seed of the covenant. (There is some dispute as to whether Ishmael was a child of God or not. But, notice: 1) he is called always the seed of the flesh in distinction from Isaac who is the seed of the promise; and is a picture of all the reprobate seed of the covenant. 2) Paul’s words are surely conclusive: “Cast out the bondwoman and her son: for the son of the bondwoman shall not be heir with the son of the freewoman.” 3) Ishmael’s “blessing” of becoming a great nation was not the blessing of God’s favor and love, but a temporal and material prosperity that was granted to him for Abraham’s sake.) As the reprobate seed of the covenant, he could not be heir with the child of the promise. He had to be banished from the home, for he rejected, in his sin, the promises of God. Thus he is a picture of the apostate and reprobate seed that is always born in the covenant, that receives the mark of the covenant, but that must be, when sin becomes manifested, cut off from the Church of Christ. Cf. also Rom. 9:4-8.

Thus also Ishmael’s life is preserved in the desert by a miracle of a well of water in order that God may make of Ishmael a mighty nation as He said.

This entire significant section closes with a description of a treaty that is made between Abraham and Abimelech after the dispute over a well of water is settled. This treaty is the only one of its kind mentioned in Scripture between Abraham and the inhabitants of Canaan and is proof of Abimelech’s spiritual character. Here Abraham found rest for some years—in Beersheba, the “well of seven” named after the seven ewes that Abimelech received as a witness that the well was Abraham’s.