Contradiction with Genesis 17:19
Galatians 4:22 refers to Abraham's two sons, which does not emphasize the divine promise as directly as Genesis 17:19 does, suggesting a singular focus on Isaac as the son born of promise.
Genesis 17:19: And God said, Sarah thy wife shall bear thee a son indeed; and thou shalt call his name Isaac: and I will establish my covenant with him for an everlasting covenant, [and] with his seed after him.
Contradiction with Genesis 21:10-12
Galatians 4:22 mentions two sons but does not emphasize Sarah’s insistence on Ishmael not sharing the inheritance with Isaac, which is a point of contradiction regarding their status.
Genesis 21:10-12: 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.
Contradiction with Romans 9:7-9
Galatians 4:22 mentions the two sons without noting the emphasis Romans places on Isaac being the child of promise and not merely a son of Abraham.
Romans 9:7-9: Neither, because they are the seed of Abraham, [are they] all children: but, In Isaac shall thy seed be called.
Contradiction with Hebrews 11:18
Galatians 4:22 simply states the existence of two sons, but Hebrews highlights the prophecy concerning Isaac as the fulfillment of God’s promise to Abraham, implying a singular significance to Isaac.
Hebrews 11:18: Of whom it was said, That in Isaac shall thy seed be called: [of: or, to]