Problem: Abraham was told here, “Take now your son, your only son Isaac.” However, Abraham had Ishmael many years before (Gen. 16) and he also had other “sons” (Gen. 25:6).
Solution: The other sons of Genesis 25 were probably born later, being mentioned three chapters after Isaac is called his “only son.” Furthermore, they were sons by “the concubines which Abraham had” (Gen. 25:6) and were not counted as heirs of God’s promise. Likewise, Ishmael was conceived in unbelief by a concubine and not counted as heir to the promised inheritance. In addition, the phrase “only son” may be equivalent to “beloved son” (cf. John 1:18; 3:16), that is, a special son. God said clearly to Abraham, “in Isaac your seed shall be called” (Gen. 21:12).
