21 Tell me, you who want to be under the law, are you not aware of what the law says? 22 For it is written that Abraham had two sons, one by the slave woman and the other by the free woman. 23 His son by the slave woman was born according to the flesh, but his son by the free woman was born as the result of a divine promise.
24 These things are being taken figuratively: The women represent two covenants. One covenant is from Mount Sinai and bears children who are to be slaves: This is Hagar. 25 Now Hagar stands for Mount Sinai in Arabia and corresponds to the present city of Jerusalem, because she is in slavery with her children. 26 But the Jerusalem that is above is free, and she is our mother. 27 For it is written:
“Be glad, barren woman,
you who never bore a child;
shout for joy and cry aloud,
you who were never in labor;
because more are the children of the desolate woman
than of her who has a husband.”
Paul continues his argument against the law and the wrong understanding of the law, and turns to the Old Testament for an illustration to confirm what he says. The story he chooses is that of Abraham and his two sons, Ishmael and Isaac. The first impression we have on reading this passage is that this is by no means an obvious illustration of the point Paul is trying to make; it sounds rather complicated and involved, representing a rather arbitrary use of Scripture, allegorising in an unusual manner. Indeed, many regard this as the most difficult passage in the epistle. Who, it might be said, in reading the story in Genesis 16/17, would have imagined it to have had an allegorical meaning of this nature, to have any other meaning, in fact, than its obvious, literal meaning? This opens up a biggish issue on the interpretation of Scripture in general. We need first of all to know the meaning of the terms that are used in this field. There are three, in the main, that are in frequent use in this field of interpretation - parable, allegory, type. A parable is distinct from the other two in that it bears one main message, and the various details of the parable are not meant in the main to convey particular truth. In this it is distinguished from the allegory, which does have a point-by-point comparison and agreement. Again, a type means a 'shadowy outline', but an allegory means that an event may have a spiritual significance over and above the historical, as here. To say that this story is an allegory does not, however, mean that it was originally written with an allegorical meaning in mind, still less that the historical truth of it is in dispute. Paul certainly regards the history as true, but shows it also had a prophetical and doctrinal significance.