Only Son

Genesis 22:2 Then God said, "Take your son, your only son, Isaac, whom you love and go to the region of Moriah. Sacrifice him there as a burnt offering on one of the mountains I will show you."

Indeed, Abraham had many sons as we're told in Genesis 25, but these sons were born later. The recently banished Ishmael in Genesis 21:14-16 was also Abraham's son, but he was conceived by a concubine and therefore not heir to the promised inheritance (Gal. 4:21-31). God had told Abraham, "It is through Isaac that your offspring will be reckoned." (Gen. 21:12; cf. Heb. 11:18). So, Isaac was a special or "beloved" son. Isaac's death would have meant the end of the line of promise (Jer. 6:26; Amos 8:10; Zec.12:10). God also has many sons (John 1:12; Rom. 8:14; Phil. 2:15; 1 John 3:1; 3:2), but one "beloved son" (Matt. 3:17; Mark 1:11; Luke 3:22; John 1:18; 3:16; 2 Pet. 1:17).

The language used here was to show that Isaac was a special son, the son of a free-woman and not the son of a bond-woman, the son of promise that was later to be understood as a shadow or type of Christ.