21 Tell me, ye who are desirous of being under law, do ye not listen to the law? 22 For it is written that Abraham had two sons; one of the maid servant, and one of the free woman. 23 But he [that was] of the maid servant was born according to flesh, and he [that was] of the free woman through the promise. 24 Which things have an allegorical sense; for these are two covenants: one from mount Sinai, gendering to bondage, which is Hagar. 25 For Hagar is mount Sinai in Arabia, and corresponds to Jerusalem which [is] now, for she is in bondage with her children; 26 but the Jerusalem above is free, which is our mother. 27 For it is written, Rejoice, thou barren that bearest not; break out and cry, thou that travailest not; because the children of the desolate are more numerous than [those] of her that 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.