These verses present an allegory or a story in which people, things, and happenings have a symbolic meaning. Abraham had two sons—one by a servant maid, the other by his wife. Hagar, the servant, represented the covenant at Mount Sinai; Sarah, the free woman, represented the covenant of grace and the gospel church state. Also, their two sons represented two sorts of professors-legalists and evangelical Christians. True believers in Christ are like Isaac, children of promise; legalists are like Ishmael, men after the flesh.
(Vs. 21) Tell me, ye that seek to be justified by the law and seek acceptance with God by obedience to the law, do you not hear what the law really says? The law never speaks peace or pardon but declares us all to be guilty (Rom. 3: 19-20). It sentences us to wrath and condemnation. Do you want to be under such a law?
(Vs. 22-23) Abraham had two sons. Ishmael was born of a servant, so he was but a servant himself and NOT THE HEIR. Isaac was born of a free woman who was joined in the family with her husband; therefore, Isaac was no servant but a free man, EVEN THE HEIR. A second principle is here intended. Ishmael was "born after the flesh," or by the ordinary strength of nature (his mother being a young woman fit for conception). Isaac was not conceived from such a principle. His mother was ninety years old and unable to bear children, so he was born BY PROMISE, or by the miracle of God.
1. The covenant of grace UNDER THE OLD ADMINISTRATION, which was greatly mistaken (it was never given to save) and was degenerated into a covenant of works by those who adhered to it.
2. The covenant of grace UNDER THE NEW ADMINISTRATION (Heb. 8:7-8).
The Sinai covenant was prefigured by Hagar, the servant, by the effect which it produced if life and acceptance are sought by it. IT PRODUCES CHILDREN OF BONDAGE! It cannot produce heirs of life. It speaks of human works, merit, and fear and is like Jerusalem today in bondage to the law, sin, and the wrath of God. Followers of the law can no more be heirs of God than Ishmael, son of the bondswoman, can be the true heir of Abraham. He will always be the servant, not the son.
(Vs. 26) Here Paul describes the covenant of grace in Christ—our Mediator, our Representative, our sin-offering. The Messianic kingdom of Christ is from above, not from Sinai. The righteousness is in His obedience, not in ours. Its redemption is in His sacrifice and His satisfaction, not in the ordinances of the tabernacle. Its access to the throne of God is through CHRIST, OUR GREAT HIGH PRIEST, not through an earthly priesthood! This covenant is free from the curse of the law and from the bondage of the law and is the mother of every believer, Jew and Gentile. We are born of grace.
(Vs. 27) This is a prophecy from Isaiah 54:1 and seems to refer to the church as it was in the early days after our Lord's death and under the ministry of the apostles. There were a few believers in a few cities, but the Lord promises that she shall be a fruitful mother with many children.
(Vs. 28) We believers are the children of promise, as Isaac was.
1. As Isaac was promised to Abraham, we were promised and given to the Lord Jesus Christ (John 6:37-39; Eph. 1:3-4) .
2. As Isaac was conceived and born beyond the strength and course of nature, we are born spiritually by the power of God (John 1:12-13).
3. As Isaac was the heir by birth as the son of Abraham, we are heirs of God and joint-heirs with Christ (Rom. 8:16-17).
(Vs. 29) Ishmael, THE SON OF FLESH, mocked and persecuted THE SON OF PROMISE. Even so, the false prophets of justification by works and advocates of the Levitical Law for acceptance with God will and do mock and persecute all who trust and rest only in Christ for justification and redemption. Salvation by works and salvation by grace are opposite and contrary. True believers mock and persecute no one, but those who trust in their works and deeds have always hated and persecuted children of promise.
(Vs. 30) Ishmael, the child of flesh and works, had to be cast out along with the mother who produced him. He could not be an heir with the true son. Even so, the system of works and human merit must be forsaken from our hearts, from our churches, and from our fellowship along with the children of flesh which this system produces. The heirs of God are the children of His grace in Christ Jesus. The self-righteous, the justified-by-works, the part-Christ-and-part flesh advocates CANNOT be heirs with children of promise.
(Vs. 31) So then, we who are born again are not children of the law, of the natural flesh; but WE ARE SUPERNATURAL CHILDREN OF FREE GRACE. To God be all the glory!