How many sons did Abraham have?
Paul's question in Galatians 4 is not really about arithmetic. He turns the family history of Abraham into an argument, and the count of two sons is the hinge on which he swings the Galatians away from law and back to grace.
Two Sons, Two Parties
The people Paul writes to were being pushed toward keeping the law, and they leaned on Abraham as their great example. So he takes them to Abraham's household and asks which son they resemble.
William KellyLook at Abraham and his house; look at the servant Hagar; look at Isaac and Ishmael. There you have in a figure the two parties that are still found on the earth: the law party symbolized by Ishmael, the child of flesh; and those who cling to the grace of God, who have their pattern in Isaac, the child of promise... The apostle deliberately reasons from Abraham, since they were always eager to quote Abraham, the father of circumcision. Their main support, as they thought — Abraham — had two sons; but according to Scripture the two stood on wholly different principles... Which son represented them? Under which type did they fall — Ishmael or Isaac? Whom did their principle make them resemble?
One by Flesh, One by Promise
The two sons had two mothers, and each birth came about in a completely different way.
Hamilton SmithAbraham had two sons by different women, one a servant and the other a free woman. The son by the servant "was born according to the flesh," entirely according to the will of man. The other, by the free woman, was born by the sovereign intervention of God.
Ishmael was the product of a plan. Abraham and Sarah, tired of waiting, tried to secure God's promise by their own arrangement.
Leslie M. GrantInterposing their own cleverness, Abram had a son by the servant woman, Hagar. What a striking picture of Israel seeking to obtain the promise of God by their own righteousness, by their law-keeping!... So Abraham, trying to establish God's promise in his own way, showed no real faith in the promise being entirely God's promise.
The Mothers Stand for Two Covenants
Paul reads the two women as a picture of two whole systems of dealing with God.
Hamilton SmithThese two women set forth the two covenants; one of law, which makes the blessing depend on man carrying out his part of the covenant; the other the covenant of promise, in which the blessing for man depends entirely on the sovereign grace of God. Moreover, the two sons set forth the two conditions that result from these covenants; the one a condition of bondage, the other of liberty.
That contrast is not just ancient history. It describes what happens whenever we try to earn what God gives.
Michael HardtLaw is for servants, liberty for sons... The application is that the minute we want to obtain blessing based on our own initiatives, actions, strength, goodness, power, whatever, we are using "works of law" and are therefore on the ground of bondage, not the liberty to which we are called as sons — as Isaac had the place of son and heir.
The Other Sons Genesis Records
If the question is simply how many sons Abraham fathered, the Old Testament records more than two. After Sarah died he married again, and six more sons followed.
The Bible TreasuryAbram took Keturah after Sarah's death, when he was at least 137 years old, and had six sons afterwards (Genesis 25:1-2).
Those six were Zimran, Jokshan, Medan, Midian, Ishbak and Shuah. Counting Ishmael and Isaac, that makes eight sons in all. But Genesis itself sorts them by standing, not by number.
William KellyStill it is written that "Abraham gave all he had to Isaac." The risen son is the heir of all things; and if we are Christ's, then we are Abraham's offspring, heirs according to promise. But to the sons of the concubines Abraham had, Abraham gave gifts, and sent them away. They receive gifts, not the inheritance of the promises; and they are sent away, instead of remaining in the house forever, as the son does.
The Two Cannot Live Together
Once Isaac was born, the household could not hold both principles at once.
C. H. MackintoshNothing could be more marked than the dividing line between, not only the two covenants, but the two offspring. They are totally distinct from each other, and can never by any means be made to blend. Abraham was made to feel this, painfully. "Cast out this slave woman with her son, for the son of this slave woman shall not be heir with my son Isaac" (Gen. 21:10). Here the natural result shows itself. The two elements could not mix.
Summary
- Eight in fact. Ishmael, Isaac, and six sons by Keturah, born after Sarah's death, when Abraham was at least 137.
- Two in argument. Paul counts only the son of the servant and the son of the free woman, because those two stand on wholly different principles.
- Two births. One came by the will of man, the other by God's sovereign intervention — effort versus promise.
- Two outcomes. The mothers picture two covenants: blessing that depends on man's performance, and blessing that depends entirely on grace; one produces bondage, the other liberty.
- One heir. The other sons received gifts and were sent away; Isaac received everything and stayed in the house — and the two principles could never be made to blend.