Once again we find that there is nothing inconsistent about the passages above.
Abraham did indeed have two sons.
Isaac, however, was called his only begotten son.
Only begotten comes from the Greek monogené̄s which means “unique, one of a kind.”
Isaac was indeed one of a kind. He was a different sort of son than Ishmael. Ishmael was born through fleshly effort, while Isaac was given according to promise.
Isaac was also viewed by God as unique in that God’s promises to Abraham would be fulfilled through Isaac.
Once again we find that God’s Word stands against the critics.
It always has.
It always shall.