Galater 4:21

desire--of your own accord madly courting that which must condemn and ruin you. do ye not hear--do ye not consider the mystic sense of Moses' words? [GROTIUS]. The law itself sends you away from itself to Christ [ESTIUS]. After having sufficiently maintained his point by argument, the apostle confirms and illustrates it by an inspired allegorical exposition of historical facts, containing in them general laws and types. Perhaps his reason for using allegory was to confute the Judaizers with their own weapons: subtle, mystical, allegorical interpretations, unauthorized by the Spirit, were their favorite arguments, as of the Rabbins in the synagogues. Compare the Jerusalem Talmud [Tractatu Succa, cap. Hechalil]. Paul meets them with an allegorical exposition, not the work of fancy, but sanctioned by the Holy Spirit. History, if properly understood contains in its complicated phenomena, simple and continually recurring divine laws. The history of the elect people, like their legal ordinances, had, besides the literal, a typical meaning (compare Co1 10:1-4; Co1 15:45, Co1 15:47; Rev 11:8). Just as the extra-ordinarily-born Isaac, the gift of grace according to promise, supplanted, beyond all human calculations, the naturally-born Ishmael, so the new theocratic race, the spiritual seed of Abraham by promise, the Gentile, as well as Jewish believers, were about to take the place of the natural seed, who had imagined that to them exclusively belonged the kingdom of God.

In these verses the apostle illustrates the difference between believers who rested in Christ only and those judaizers who trusted in the law, by a comparison taken from the story of Isaac and Ishmael. This he introduces in such a manner as was proper to strike and impress their minds, and to convince them of their great weakness in departing from the truth, and suffering themselves to be deprived of the liberty of the gospel: Tell me, says he, you that desire to be under the law, do you not hear the law? He takes it for granted that they did hear the law, for among the Jews it was wont to be read in their public assemblies every sabbath day; and, since they were so very fond of being under it, he would have them duly to consider what is written therein (referring to what is recorded Gen. 16 and 21), for, if they would do this, they might soon see how little reason they had to trust in it. And here, 1. He sets before them the history itself (Gal 4:22, Gal 4:23): For it is written, Abraham had two sons, etc. Here he represents the different state and condition of these two sons of Abraham - that the one, Ishmael, was by a bond-maid, and the other, Isaac, by a free-woman; and that whereas the former was born after the flesh, or by the ordinary course of nature, the other was by promise, when in the course of nature there was no reason to expect that Sarah should have a son. 2. He acquaints them with the meaning and design of this history, or the use which he intended to make of it (Gal 4:24-27): These things, says he, are an allegory, wherein, besides the literal and historical sense of the words, the Spirit of God might design to signify something further to us, and that was, That these two, Agar and Sarah, are the two covenants, or were intended to typify and prefigure…

4:21-31 Paul now returns to arguing from Scripture, using the contrast between Hagar and Sarah and between their children. Paul argues for a similar contrast between those who are slaves under the law and those who are free in Christ. • Paul’s argument uses the allegorical techniques of rabbinic Judaism (see study note on 4:24). Having been trained as a rabbi (Acts 22:3), Paul could out-argue the Judaizers using their own methods. 4:21 do you know what the law actually says? They were trying to achieve righteousness by the law, but they did not truly understand its meaning (cp. Luke 24:25-27; 1 Tim 1:7).