The Son of Promise
“And the LORD visited Sarah as he had said, and the LORD did unto Sarah as he had spoken,” Genesis 21:1.
The Lord kept His promise to Sarah and sent to her the son He had promised. Sarah had waited 90 years for this son, Abraham had waited 100 years. Though it was a long wait, God was faithful. No one ever waits in vain who waits in faith for the promise of God. That was Abraham’s experience; he leaned upon the Word of God and the promise of God.
Fourteen years earlier Abraham had tried to help God out by having a son by Hagar. He had to learn that the efforts of his flesh nature were of no value in God’s sight. Ishmael was of no use whatever in God’s sight and in God’s purposes. God was in no hurry, he could wait fourteen years for Abraham to learn the futility of the efforts of the flesh.
The flesh nature can never do anything for God. The Lord must visit, and the Lord must do, and faith must wait. The flesh nature must be totally set aside as worthless, then the glory of God can shine forth, and faith can enjoy its reward.
Verse 2, “For Sarah conceived, and bare Abraham a son in his old age, at the set time of which God had spoken to him.” God has His set time, His due season, and the faithful must be content to wait. The time may seem long, and the heart may grow weary in its waiting, but the spiritual man will find comfort and strength in the promise of God.
Abraham was a hundred years old when his son was born to him. In his natural man he had nothing to glory in. Abraham’s extremity was God’s opportunity to reveal Himself in all His glory.
Isaac demonstrated a principle. He was to the household of Abraham, what the receiving of the new nature is to the soul of sinner. It was not Ishmael changed, but Isaac born. The son of the bondwoman could never be anything but a slave. Ishmael might become a great nation, he might dwell in the wilderness and become an archer, he might become the father of twelve princes, but he would always be the son of a bondwoman.
On the other hand no matter how weak and despised Isaac might be, he was and always would be the son of the free-woman. Isaac’s position and character, his standing and prospects, were from the Lord. “That which is born of the flesh is flesh; and that which is born of the Spirit is spirit.” Regeneration is not a change of the old nature, but the birth of a new nature.
We also know that the introduction of the new nature does not change in the slightest degree, the character of the old nature. The old nature is irredeemable, it cannot be reformed, and it is cursed. “For the flesh lusteth against the Spirit, and the Spirit against the flesh: and these are contrary the one to the other: so that ye cannot do the things that ye would.” (Galatians 5:17)
The doctrine of the two natures is much misunderstood, but not because the scriptures are unclear on it. “Because the carnal mind is enmity against God: for it is not subject to the law of God, neither indeed can be.
So then they that are in the flesh cannot please God.” (Romans 8:7-8)
Colossians 3:9-10, “Lie not one to another, seeing that ye have put off the old man with his deeds; And have put on the new man, which is renewed in knowledge after the image of him that created him:” The only remedy for the old man, or the old nature, is to put it off, to count it as dead.
The birth of Isaac did not improve Ishmael, but only brought out his opposition to the child of promise. The remedy is given in verses 10-12, “Wherefore she said unto Abraham, Cast out this bondwoman and her son: for the son of this bondwoman shall not be heir with my son, even with Isaac.
And the thing was very grievous in Abraham's sight because of his son.
And God said unto Abraham, Let it not be grievous in thy sight because of the lad, and because of thy bondwoman; in all that Sarah hath said unto thee, hearken unto her voice; for in Isaac shall thy seed be called.”
We are not called to try to improve on the old nature or pamper it; we are to count as dead.