21 Tell me, you who desire to be under the law, do you not hear the law? 22 For it is written that Abraham had two sons: the one by a bondwoman, the other by a freewoman. 23 But he who was of the bondwoman was born according to the flesh, and he of the freewoman through promise, 24 which things are symbolic. For these are the two covenants: the one from Mount Sinai which gives birth to bondage, which is Hagar-- 25 for this Hagar is Mount Sinai in Arabia, and corresponds to Jerusalem which now is, and is in bondage with her children-- 26 but the Jerusalem above is free, which is the mother of us all. 27 For it is written: "Rejoice, O barren, You who do not bear! Break forth and shout, You who are not in labor! For the desolate has many more children Than she who has a husband."
Matthew Henry's Commentary on Galatians 4:21-27
Commentary on Galatians 4:21-27
(Read Galatians 4:21-27)
The difference between believers who rested in Christ only, and those who trusted in the law, is explained by the histories of Isaac and Ishmael. These things are an allegory, wherein, beside the literal and historical sense of the words, the Spirit of God points out something further. Hagar and Sarah were apt emblems of the two different dispensations of the covenant. The heavenly Jerusalem, the true church from above, represented by Sarah, is in a state of freedom, and is the mother of all believers, who are born of the Holy Spirit. They were by regeneration and true faith, made a part of the true seed of Abraham, according to the promise made to him.