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. ... Now you, brothers and sisters, like Isaac, are children of promise. (Gal 4,22-26.28)
When we think of the sons of Abraham, it is good to realize that they are a picture of spiritual realities that are in contrast as two modes of spiritual life. In the first, man, literally "flesh," his strength and ability, plays a role. Man is supposed to do things, and God should accept them.
The second mode is the total reliance on God, because the man knows that he can do nothing that is worth anything to God. Only what comes from Him, what is born from above, is of eternal value. Thus the eternal life itself is born in man - without our merit, as a gift from heaven.
But whenever set the two sons in contrast, it must also be emphasized that both bore some measure of the likeness of Abraham - Ishmael was no foreign outcast! It seems puzzling (as it was for Abraham) that they should be separated, that in the end only one was allowed to remain and the other had to go.
Apart from the very practical danger to Isaac, that we have already mentioned, Ishmael and Isaac here represent exactly those incompatible spiritual realities. Like their mothers, they reflect two covenants, but only one of which rests not on the efforts of man (by the power of "the flesh") but on the power of God Himself from above, and is therefore eternal.
What is remarkable about the whole thing is that Paul (seen by some as a great legalist) divides the two covenants according to the degree of inner freedom! The old covenant, which like Ishmael no doubt also bears the marks of God the Father, leads ultimately to bondage. Not intentionally, but because of man's inability to truly fulfill it. Because he lacks the power to live by it, commands are created, systems of regulations that grip the soul and regulate the whole of life. Man strives in vain for something with which only his mind is in harmony, but not his nature. Outwardly he may agree with the morality of the Law, but inward is out of harmony with it.
"But the future Jerusalem is free, and this is our mother." It is only Jesus, the promised Isaac, born into freedom, who sets his followers free and brings them to the heights of life from God, by the transformation of the inward man through the working of the power of the Holy Spirit.f course, if they have truly known him and not departed from him on their journey, like the Galatians.
