Christ bought us back from the curse [caused by our not obeying all the requirements] of the law of Moses; He became a curse for us [by dying on the cross], for it is written [Deut. 21:23], "Every one who hangs on a tree [i.e., a cross] is cursed [i.e., cut off from God]."

But before faith [in Christ] became available, we [Jews] were kept in bondage under [condemnation for not obeying perfectly] the law of Moses. [This condition existed] until the faith [i.e., the Gospel message] was made known [to people].

So, the law of Moses became like our "transportation to school," bringing us to [the school of] Christ where we [learn how to be] made right with God by faith [in Christ].

This set of circumstances contains an illustration; for these two women [Hagar and Sarah] represent the two Agreements [between God and mankind]. The one [Agreement], given at Mount Sinai, represents Hagar, whose children became [the Israelites], enslaved under bondage [to the requirements of the law of Moses].