Ishmael and Isaac Represent Two Covenants (the ONE old covenant and the ONE new covenant)
Many have been confused over the allegory Paul used to illustrate the Old and New Covenants. Here is the way he wrote about it: "For it is written, that Abraham had two sons, the one by a bondmaid, the other by a free-woman. But he who was of the bondwoman was born after the flesh; but he of the freewoman was by promise. Which things are an allegory: for these are the two covenants; the one from the mount Sinai, which gendereth to bondage, which is Agar. For this Agar is mount Sinai in Arabia, and answereth to Jerusalem which now is, and is in bondage with her children." Galatians 4:22-25.
Paul portrays Isaac and Ishmael, the two sons of Abraham, as representing the Old and New Covenants. He plainly shows that Hagar's son, Ishmael, symbolizes the Old Covenant, and Sarah's son, Isaac, is a type of the New Covenant. "Now we, brethren, as Isaac was, are the children of promise. ... So then, brethren, we are not children of the bondwoman, but of the free." Verses 28-31.
This is interesting. How do those sons of those two women represent the two covenants? God had promised Abraham a son by his wife Sarah, but because she was almost 90 years old, neither of them believed such a thing could happen. Sarah knew that her womb was dead and that she was long past the age for bearing children. So she suggested that her husband take Hagar, her handmaid, and have a child by her. It seemed the only way to rescue God from an impossible promise. In time, Abraham yielded to the face-saving device and had a child by Hagar.
Here is an exact illustration of the Old Covenant principle of "we will do." Abraham tried to work it out in the flesh, according to human effort and planning. The old arrangement failed just as surely as the Old Covenant promises failed, because there was no dependence on divine power. God did not ever recognize Ishmael as the promised seed.
When Isaac was born, it was a miracle. God actually created a new life out of a biologically barren womb. The physical impossibilities yielded to the supernatural, creative power of God. Isaac perfectly represents the principle of the New Covenant relationship based upon regeneration, a new-birth experience, which begets the life of the Son of God in all who believe. The natural, physical womb of Sarah was totally incapable of producing any fruit. In the same way, the natural, carnal body and mind of a sinner cannot bring forth the fruit of obedience. When God used His power to create a new life within Sarah, the impossible happened, and she bore a son. When God uses His power to create new life in the soul, the impossible happens again - a human being becomes spiritual and obedient.
Isaac was not "born after the flesh," but "after the Spirit." Galatians 4:29. Because man is carnal and "weak in the flesh," he has no power to attain to the righteousness of the law. He, too, must be born after the Spirit. Every attempt to obey on the Old-Covenant basis of human effort will produce only children of bondage. The law must be written into the heart by the Holy Spirit and fulfilled by "Christ in you."
This allegory of Hagar and Sarah clears up another very important point of truth. Those who are under the Old Covenant are the commandment breakers, and those under the New Covenant are the commandment keepers. It was only when Abraham disobeyed God by taking Hagar that he fulfilled the principle of the Old Covenant. When he trusted God to give him a son through Sarah, he was being obedient to God's will, and properly represents the New-Covenant Christians. Yet how often do modern interpreters get these facts confused! They accuse law-keepers of being under the Old Covenant. The truth is exactly the opposite. The law is not really kept until it is written on the heart of the transformed believer. Then it becomes the mark of identification - the love symbol - for those who are born of the Spirit. Jesus said, "If ye love me, keep my commandments." John 14:15. John wrote, "For this is the love of God, that we keep his commandments." 1 John 5:3.
