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.”
The controversy Paul is dealing with in Galatians centres upon the claim of the Jews to be the sons of Abraham, and because so, to be heirs of eternal blessing. That this was a major issue at the time of the establishment of the gospel we can see in the gospel record itself. 'We have Abraham to our father' (Luke 3:8), said the Jews to John the Baptist; and 'We be Abraham's seed' (John 8:33), they said to Jesus. Paul's point is this: Abraham had two sons, one of a bondwoman, the other of promise. And, as this was so, there are two posterities flowing from him, a natural one, comprising all the natural descendants, and one according to promise, the spiritual, who through like faith with Abraham, became Abraham's children. Therefore, the alternative to being in the line of promise is to be in the natural line, and Paul shows here what happened to it: (a) it went into bondage. To be the son of a bondwoman was to be born into the realm of servitude and slavery. There was no way out of this, it was natural and inevitable; (b) it meant being cast out and having no part in the inheritance of promise. This, in fact, is the double truth about those who insist on remaining under the law - 'working their passage' to heaven, seeking to earn their salvation by good works. They are in bondage, not least to a constant anxiety about salvation! They have no assurance, and through fear of death they spend their lifetime under bondage. And they are cast out eternally. 'Depart from Me', says Christ, 'I never knew you'. Seen from this standpoint Paul's illustration is not only relevant, but urgently challenging.