"Tell me, ye that desire to be under the law, do ye not hear the law? For it is written, that Abraham had two sons, one by the handmaid, and one by the freewoman. Howbeit the _son_ by the handmaid is born after the flesh; but the _son_ by the freewoman _is born_ through promise. Which things contain an allegory: for these _women_ are two covenants; one from mount Sinai, bearing children unto bondage, which is Hagar. For Sinai is a mountain in Arabia, and answereth to the Jerusalem that now is: for she is in bondage with her children. But the Jerusalem that is above is free, which is our mother. For it is written,
Rejoice, thou barren that bearest not; Break forth and cry, thou that travailest not: For more are the children of the desolate than of her which hath the husband.
Now we, brethren, as Isaac was, are children of promise. But as then he that was born after the flesh persecuted him _that was born_ after the Spirit, even so it is now. Howbeit what saith the scripture? Cast out the handmaid and her son; for the son of the handmaid shall not inherit with the son of the freewoman. Wherefore, brethren, we are not children of a handmaid, but of the freewoman. For freedom did Christ set us free: stand fast therefore, and be not entangled again in a yoke of bondage."--GAL. iv. 21-v. 1.
The Apostle wished that he could "change his voice" (ver. 20). Indeed he has changed it more than once. "Any one who looks closely may see that there is much change and alteration of feeling in what the Apostle has previously written" (Theodorus). Now he will try another tone; he proceeds in fact to address his readers in a style which we find nowhere else in his Epistles. He will tell his "children" a story! Perhaps he may thus succeed better than by graver argument. Their quick fancy will readily apprehend the bearing of the illustration; it may bring home to them the force of his doctrinal contention, and the peril of their own position, as he fears they have not seen them yet. And so, after the pathetic appeal of the last paragraph, and before he delivers his decisive, official protest to the Galatians against their circumcision, he interjects this "allegory" of the two sons of Abraham.
Paul cites the history of _the sons of Abraham_. No other example would have served his purpose. The controversy between himself and the Judaizers turned on the question, Who are the true heirs of Abraham? (ch. iii. 7, 16, 29). He made faith in Christ, they circumcision and law-keeping, the ground of sonship. So the inheritance was claimed in a double sense. But now, if it should appear that this antithesis existed in principle in the bosom of the patriarchal family, if we should find that there was an elder son of Abraham's flesh opposed to the child of promise, how powerfully will this analogy sustain the Apostle's position. Judaism will then be seen to be playing over again the part of Ishmael; and "the Jerusalem that now is" takes the place of Hagar, the slave-mother. The moral situation created by the Judaic controversy had been rehearsed in the family life of Abraham.
"Tell me," the Apostle asks, "you that would fain be subject to the law, do you not know what it relates concerning Abraham? He had two sons, one of free, and the other of servile birth. Do you wish to belong to the line of Ishmael, or Isaac?" In this way Paul resumes the thread of his discourse dropped in ver. 7. Faith, he had told his readers, had made them sons of God. They were, in Christ, of Abraham's spiritual seed, heirs of his promise. God had sent His Son to redeem them, and the Spirit of His Son to attest their adoption. But they were not content. They were ambitious of Jewish privileges. The Legalists persuaded them that they must be circumcised and conform to Moses, in order to be Abraham's children in full title. "Very well," the Apostle says, "you may become Abraham's sons in this fashion. Only you must observe that Abraham had _two_ sons. And the Law will make you his sons by Hagar, whose home is Sinai--not Israelites, but _Ishmaelites_!"