Isaac, Abraham's "only" son

Somehow, every time I read Genesis 22, I always manage to skip over where God says that Isaac is Abraham’s only son. What happened to Ishmael? Well, when Sarah made Abraham send Hagar and Ishmael away, he basically had to disown them because he was kicking them out of the household. So even though God had promised Abraham that he would bless Ishmael along with Isaac, Ishmael was denied his rights as Abraham’s son and could not receive an inheritance from his father; his only inheritance would be what God gave him.
This puts the sacrifice of Isaac into a new perspective. Usually I think, “Wow, for Abraham to sacrifice his only son must take a lot of faith,” but I don’t even think about Ishmael. Now the sacrifice seems even greater because not only was Abraham about to sacrifice Isaac, his only son, but he had also just disowned his only other heir. If he killed Isaac, he no longer had a back-up plan for his inheritance. But he went to sacrifice Isaac anyway, knowing that God must have something planned. This is a huge shift in Abraham’s way of thinking: back in chapter 16, Abraham doubted God’s promise to give him a son through Sarah, so he took matters into his own hands and had Ishmael with Hagar. After all, God had said that Abraham’s heir would be “a son coming form your own body,” not “from Sarai’s body (Genesis 15:4). But now in chapter 22, Abraham only has Isaac left, but he agrees to follow through with the sacrifice anyway. Of course, he could have gone against Sarah and went in search of Ishmael to bring him home and make him his son again, but he didn’t.

A lot of times we like to have back-up plans when God tests us. We say we believe God will pull through for us, but we always have something stored up just in case. “Who knows? Maybe His plan is for us to use what we already have instead of waiting for Him to give us something new.” I know I’m guilty of this. But what would we do if God took away our Plan B? Would we disobey God so we can have the security of knowing that God’s promise is still possible? Did Abraham think, “Well, Isaac is my only son now. And God, You told me he would be my heir, so I don’t think sacrificing him would be the right thing to do”? Maybe, but he didn’t act on it. When Abraham’s Plan B fell through, his only options were complete obedience or complete disobedience. Sometimes God has to take away our Plan B in order for us to see that. He has to remove Satan’s lies and deception in order for us to see that Plan B isn’t just another way to succeed if Plan A fails, it’s outright distrust. Resorting to Plan B shows that we don’t really think God can make Plan A work. I pray that we would be like Abraham in his later life, that when God gives us a task to do, we would recognize it as a necessary step in fulfilling His ultimate purpose, and then do it.