How many sons did Abraham have?

Question

Genesis says that Abraham only had one son (Gen. 22:2) and Paul says he had two (Gal. 4:22). It seems like the Bible can't get its history correct?

Answer

Genesis 22:2: He said, "Take your son, your only son Isaac, whom you love, and go to the land of Moriah, and offer him there as a burnt offering on one of the mountains of which I shall tell you."
Galatians 4:22: For it is written that Abraham had two sons, one by a slave woman and one by a free woman.

Actually, Abraham had many sons besides Isaac and Ishmael. He and his wife Keturah had six more (Gen. 25:1-2). Since Moses wrote Genesis, he was very familiar with this fact. Paul, being a Pharisee, was familiar with the book of Genesis as well (Phil. 3:5-6). They both knew how many sons Abraham had.

But the writers are making a specific point in their statements. Essentially, because Ishmael had been disinherited and sent away (Gen. 21:10, 14), this made Isaac the son of promise, the only beloved son (Gen. 25:1-18). Likewise, Jesus is the only begotten Son of God (Matt. 3:17; 17:5; John 3:16; Eph. 1:6; 2 Pet. 1:17), but God has many sons and daughters whom he loves as well (2 Cor. 6:18; cf. Matt. 5:9; John 1:12; Rom. 8:14, 16, 19; 9:26; Gal. 3:26; 4:5; Eph. 1:5; 1 John 3:1, etc.).

This Spirit-inspired history remains intact and correct.