²³ One, the child of the enslaved woman, was born according to the flesh; the other, the child of the free woman, was born through the promise.^(A)

¹¹ By faith, with Sarah’s involvement, he received power of procreation, even though he was too old, because he considered^[a] him faithful who had promised.^(A)

⁷ and not all of Abraham’s children are his descendants, but “it is through Isaac that descendants shall be named for you.”^{(A) 8} This means that it is not the children of the flesh who are the children of God, but the children of the promise are counted as descendants.

²⁸ Now you,^[a] my brothers and sisters, are children of the promise, like Isaac. ²⁹ But just as at that time the child who was born according to the flesh persecuted the child who was born according to the Spirit, so it is now also.^(A)

The Birth of Isaac

21 The Lord dealt with Sarah as he had said, and the Lord did for Sarah as he had promised.^{(A) 2} Sarah conceived and bore Abraham a son in his old age, at the time of which God had spoken to him.^(B)

¹⁰ Then one said, “I will surely return to you in due season, and your wife Sarah shall have a son.” And Sarah was listening at the tent entrance behind him.^{(A) 11} Now Abraham and Sarah were old, advanced in age; it had ceased to be with Sarah after the manner of women.^{(B) 12} So Sarah laughed to herself, saying, “After I have grown old, and my husband is old, shall I be fruitful?”^{(C) 13} The Lord said to Abraham, “Why did Sarah laugh and say, ‘Shall I indeed bear a child, now that I am old?’ ¹⁴ Is anything too wonderful for the Lord? At the set time I will return to you, in due season, and Sarah shall have a son.”^(D)

⁸ But what does it say?

(that is, the word of faith that we proclaim),^(A)

¹⁸ Hoping against hope, he believed that he would become “the father of many nations,” according to what was said, “So shall your descendants be.” ¹⁹ He did not weaken in faith when he considered his own body, which was already^[a] as good as dead (for he was about a hundred years old), and the barrenness of Sarah’s womb.^{(A) 20} No distrust made him waver concerning the promise of God, but he grew strong in his faith as he gave glory to God, ²¹ being fully convinced that God was able to do what he had promised.^(B)

¹⁵ God said to Abraham, “As for Sarai your wife, you shall not call her Sarai, but Sarah shall be her name. ¹⁶ I will bless her and also give you a son by her. I will bless her, and she shall give rise to nations; kings of peoples shall come from her.”^{(A) 17} Then Abraham fell on his face and laughed and said to himself, “Can a child be born to a man who is a hundred years old? Can Sarah, who is ninety years old, bear a child?”^{(B) 18} And Abraham said to God, “O that Ishmael might live in your sight!” ¹⁹ God said, “No, but your wife Sarah shall bear you a son, and you shall name him Isaac.^[a] I will establish my covenant with him as an everlasting covenant for his offspring after him.^(C)