Galatians 4:31

Wherefore, brethren, we are not children of the handmaid, but of the free woman. [Tell me, ye who are so eager to return to the law, do ye not note what the law itself says? Of itself it warns you not to do this thing, in that it tells you the story of Abraham's two sons, one of whom, Ishmael, was the son of the bondwoman, Hagar; and the other of whom, Isaac, was the son of the freewoman, Sarah. These sons, it tells you, were born differently. Ishmael, the slave-born, came into the world according to the usual course of nature; but Isaac, the freeborn, came through the promise of God, which held good even contrary to the laws of nature. Now, this history, though literally true, is, nevertheless, so designed as to contain an allegory; for these two women represent the two covenants which we have been discussing. Hagar represents the law, which came from Mt. Sinai, and which, like Hagar, bears slave-born children. Hagar, then, in earlier history, represents Mt. Sinai in Arabia with its covenant, and in later history she stands for Jerusalem, the successor to Mt. Sinai, for she, like Hagar, is in bondage; and all her children are, as to sin and the law, slave-born (John 8:32-34). Leaving out the preliminary steps, Paul rushes at once to the comparison of the two cities, for the emissaries of Jerusalem were constantly disparaging him as not the equal of those who were the heads of the church there (Galatians 2:6-7). Filling in all the steps, according to the analogy of the apostle's reasoning, the full allegory would run thus: Sarah, the freewoman, represents the gospel covenant, which, like Sarah, bears freeborn children according to God's promise, and she is now represented by the celestial Jerusalem, which, with her free children, is our mother. And the Scripture itself recognizes the order of these two covenants, showing how the law should be populous for a time, and then be excelled by the fecundity of the gospel covenant, which seemed so long barren; for Isaiah foretells it in the words, "Rejoice, etc." As for a time Hagar seemed to be the real wife, and as such to own the husband, so for centuries those of the old covenant seemed to be the real Bride and to own the Lord. Resuming the allegorical history and directly identifying the Christian with Isaac, Paul shows how the history continued to run parallel, for, as Ishmael persecuted Isaac, so the progeny of the law persecuted the children of the gospel. Then, prophetically conscious of God's design to continue the parallel to the end, he gives the final prophecy of the rejection of God's once chosen people, and closes with the incontrovertible conclusion that the Galatians are not children of the bondwoman, or law, but of the freewoman, or gospel. Thus Paul, knowing the passion of the Judaizers for allegorizing, meets them with their own weapon, and casts into this appropriate mold matter which he presents argumentatively and logically at Romans 9:6-9; and prophetically at Romans 11:15. The fact that Isaac and the gospel were both matters of promise, forestalled the Judaizers in any attempt to adjust the allegory so as to turn it against Paul. Moreover, the Jews themselves universally recognized the law as a practical bondage (Acts 15:10; Matthew 23:4), and the complaint against Paul was that he allowed too much liberty.]