Contradiction with Genesis 16:15
Genesis 15:4 promises a biological heir from Abram's own body, but in Genesis 16:15, Hagar bears Abram a son, Ishmael, suggesting another child before Isaac, complicating the promise fulfillment.
Genesis 16:15: And Hagar bare Abram a son: and Abram called his son's name, which Hagar bare, Ishmael.
Contradiction with Genesis 18:13-14
These verses emphasize that nothing is too difficult for the Lord, reaffirming God's promise, but Genesis 15:4 initially casts doubt by considering an heir through a servant.
Genesis 18:13-14: And the LORD said unto Abraham, Wherefore did Sarah laugh, saying, Shall I of a surety bear a child, which am old?
Contradiction with Genesis 21:10
Sarai's demand to cast out Hagar and Ishmael contradicts Genesis 15:4 by showing strife and complication in fulfilling the heir promise, reflecting human intervention versus divine promise.
Genesis 21:10: 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.
Contradiction with Romans 9:7-8
While Genesis 15:4 speaks of a biological heir, Romans 9:7-8 focuses on the spiritual offspring, suggesting a broader interpretation than just physical lineage.
Romans 9:7-8: Neither, because they are the seed of Abraham, [are they] all children: but, In Isaac shall thy seed be called.