Contradiction with Genesis 21:12
Contradicts Genesis 17:19 by emphasizing that although Isaac is the promised child, God's blessings would also be through Ishmael.
Genesis 21:12: 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.
Contradiction with Romans 9:7
This verse contradicts Genesis 17:19 by stating that not all who are of Israel are considered children of the promise, expanding the idea beyond just Isaac.
Romans 9:7: Neither, because they are the seed of Abraham, [are they] all children: but, In Isaac shall thy seed be called.
Paradox #1
Genesis 17:19 mentions God’s promise to establish His covenant with Isaac rather than Ishmael. Some people see a contradiction or inconsistency with earlier promises or blessings said about Ishmael, potentially raising questions about favoritism or the nature of God’s covenants. However, this is often explained as God’s specific plan and purpose through Isaac for the covenant lineage.