Two Sons

In Genesis 22 you kept referencing how the scriptures say that God told Abraham to take his “only son,” didn’t Abraham have more than one son? 

First, yes, Abraham did have more than one son. We have spent many weeks talking about Isaac and Ishmael, but in Geneses 22:2 God says Take your son, your only son Isaac, whom you love…” and when God substitutes a ram for Isaac in the sacrifice (Genesis 22:12) God says, “Do not lay your hand on the boy or do anything to him, for now I know that you fear God, seeing you have not withheld your son, your only son, from me.”
I believe your question is why does God say, “your only son,” when He knows Abraham has more than one. The answer is, don’t worry, God didn’t forget about Abraham’s other son. There are two simple explanations for this.
First, with the departure of Ishmael from Abraham’s household, Isaac had become, in that cultural mindset, Abraham’s only son.
Secondly, and more importantly, we get to look at the events of Genesis 22 through the lens of Christ. Almost every line in Genesis 22 can relate to God and His son Jesus. When God says “take your son, your only son Isaac, whom you love…” it can be related directly to Jesus’ baptism in Matthew 3:17 when God says, “This is my beloved Son, with whom I am well pleased.”
The idea of Abraham taking his only son relates to God sending his only son to die as a substitutionary atonement for people. The point is NOT that Abraham didn’t have any other son, it is Abraham taking his only son of the promise, “the son he loved,” and offering Him to God before everything else.
There are also connotations of what “love” and “hate” mean in the cultural context of the Hebrews at this time, but no one has asked me about it…so I will wait until someone does (haha).