Why did the promised seed have to come through Isaac and not through Ishmael or Esau?
The promised seed, who is Christ, had to come through Isaac because God's promise singled out Isaac's line for the singular seed. It could not take off through Ishmael or come down through Esau. It depended on God's miraculous promise to Sarah and His sovereign plan, not ordinary descent.
Les explains that the promise concerns a singular seed, not plural. The seed of the woman is Christ. Therefore the promised line could not branch off through Ishmael and could not come down through Esau; it had to come through Isaac. Les then notes the same principle appears in the next generation with Rebekah's twins. Romans 9:9 cites the word of promise: “At this time will I come, and Sarah shall have a son.” Abraham was almost 100 and Sarah almost 90; Sarah's conception required a miracle of God. That miracle was the result of God's promise, which goes back to eternity past before Adam was created. Les emphasizes God's sovereignty throughout, saying God is sovereign.
Neither, because they are the seed of Abraham, are they all children: but, In Isaac shall thy seed be called.
More Questions
Why is the word 'seed' in the promise to Abraham singular rather than plural?
The word 'seed' in the promise 'in Isaac shall thy seed be called' is singular, not plural, and refers to the coming of the one seed of the woman, who is Christ.
Is the "seed" promised to Abraham singular or plural, and who is it?
The promised "seed" in "in Isaac shall thy seed be called" is singular, not plural, and refers to the coming of the seed of the woman, who is Christ.
Why does Scripture say "in Isaac shall thy seed be called" and what does the singular "seed" mean?
"In Isaac shall thy seed be called" uses "seed" in the singular, not the plural, and that singular seed is Christ, the coming seed of the woman.
Were Ishmael and Esau's descendants children of Abraham but not children of promise?
Ishmael's offspring and Esau's offspring were physically children of Abraham, but they were not children according to the promises.
Why are not all of Abraham's descendants counted as the seed of promise?
Not all of Abraham's descendants are the seed of promise: Ishmael's and Esau's descendants were genetically children of Abraham with Abraham as their father, yet spiritually they stand outside the covenant promises.