Tell me, you who want to be under the law, are you not aware of what the law says? For it is written that Abraham had two sons, one by the slave woman and the other by the free woman. 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.
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. Now Hagar stands for Mount Sinai in Arabia and corresponds to the present city of Jerusalem, because she is in slavery with her children. But the Jerusalem that is above is free, and she is our mother. For it is written:
‘Be glad, barren woman,
you who never bore a child;
break forth and cry aloud,
you who were never in labour;
because more are the children of the desolate woman
than of her who has a husband.’
Now you, brothers and sisters, like Isaac, are children of promise. At that time the son born according to the flesh persecuted the son born by the power of the Spirit. It is the same now. But what does Scripture say? ‘Get rid of the slave woman and her son, for the slave woman’s son will never share in the inheritance with the free woman’s son.’ Therefore, brothers and sisters, we are not children of the slave woman, but of the free woman.
In this part of his letter Paul is weaving together ideas from Genesis 21:9-10 and Isaiah 54:1. Paul’s teaching could be summarised in the form of this table:
natural – not of promise
spiritual – of promise
The Law of Moses
The Gospel of Grace
Principle of Law
Principle of Grace
(Jewish people trying to force Gentiles to be circumcised)
At the time of God’s promise to Abraham, Sarah was childless. The amazing news for her was that she would be the mother of a great nation because of a miraculous supernatural birth. The challenge for Paul’s listeners was to believe that many more Gentiles would come to faith in Christ through a miraculous spiritual birth.
You may remember the passage in Isaiah from our previous series ‘Created to Grow’. The very next verse (Isaiah 54:2) starts with the words ‘Enlarge the place of your tent’. This is a promise of future church growth, but it depends on how people responded to Paul’s message.
If the Jewish believers had continued to insist that Gentile believers needed to be circumcised, the church would not have grown. It would have turned into a legalistic Jewish cult and become irrelevant within a few generations. But Paul’s letter was read carefully and preserved for us as scripture. Now we have a church spreading out to both Jews and Gentiles all over the world. We are no longer slaves to regulations that are impossible to keep; instead we are filled with the Holy Spirit and free to love our neighbour as ourselves.