The testing of Abraham was not the only reason God told Abraham to offer Isaac.  God desired to reveal something more of the way of salvation.  God wanted to reveal to Abraham and to Abraham’s seed that God provides the sacrifice.   As the knife hung over the child, “the angel of the LORD” told Abraham not to harm the child. (Gen. 22.11) Looking up Abraham sees a “ram caught in a thicket.” (Gen. 22.13) This ram is offered as a sacrifice instead of Isaac.  Isaac lives because the ram dies.  This story points to that which the Lord Jesus Christ did upon the cross of Calvary.