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.”
John Stott gives a useful summary of the argument, as follows: 'There are three stages in the argument, of this paragraph. The first is historical, the second allegorical and the third personal. In the historical verses (22, 23) Paul reminds his readers that Abraham had two sons, Ishmael, the son of a slave, and Isaac, the son of a free woman. In the allegorical verses (24-27) he argues that these two sons with their mothers represent two religions, a religion of bondage which is Judaism, and a religion of freedom which is Christianity. In the personal verses (28-31) he applies his allegory to us. If we are Christians, we are not like Ishmael (slaves), but like Isaac (free). Finally, he shows us what to expect if we take after Isaac.' The force, then, of the question in 21 is this: 'Do you know what you are letting yourselves in for, you who desire to be under the law?' And Paul proceeds to show them all that is involved in being under the law. 'Listen to the law', he cries, 'for the very law, whose servant you want to be, will be your judge and condemn you'. Indeed, the law itself rejects the law (30) and Paul's use of this story from the Old Testament shows that this is so. Such is the argument, in summary. We shall now go back to look at it in more detail.