Some older sermon notes from Pastor Paul from last year, from his teaching on Genesis 22, on the sacrifice of Isaac:
The test put before Abraham is to sacrifice his only son, the ultimate test. God never had a plan to have Isaac sacrificed: rather, this was a testing of faith. In this situation there is no mention of Sarah being told - likely she was not. What happens here is that Abraham sets out resolutely to obey.
In Hebrews, the writer states that Abraham didn't have it all figured out, but he know God could raise Isaac from the dead. The father is resolute to obey, and the son is submissive to the father. The sacrifice took place on Mt. Moriah, the same place where David sacrificed for his people. Moriah is later the site of Israel's temple in Jerusalem.
God's test here is about substitution. "the angel of the Lord" (v. 15) is considered by some to be the pre-incarnate Christ. In John 8:56, "Abraham rejoiced that he would see my day", a reference here to Genesis 22. This chapter paints a picture of the sacrifice that God makes for use. Christ's death is the pinnacle of our faith. Trials in life are reminders of what Christ endured. Abraham understood this, and we all deserve to be Isaacs on the altar because of our sin.
After the sacrifice is stopped, God reaffirms the covenant (v. 17). The provisions are for blessing, increased descendants, and to possess the land of his enemies. Abraham was willing to give up family for his walk with God. Sometimes our relationships are separated by God's will, and obedience to Christ may lead us and our family ultimately to persecution and death. Abraham knew of this, and his example is one of faithfulness to God in the most extreme situation of testing.