God’s call to Abraham to sacrifice Isaac did not come in a vacuum. It is set within a greater context of all God’s prior dealings with Abraham. In chapter 12, “Yahweh said to Abram, ‘Go from your country and your kindred and your father’s house to the land that I will show you. And I will make of you a great nation, and I will bless you and make your name great, so that you will be a blessing. I will bless those who bless you, and him who dishonors you I will curse, and in you all the families of the earth shall be blessed.’ So Abram went, as the Yahweh had told him, and Lot went with him.” Lot was Abram’s next of kin; he was counted heir of this promise. But God appeared again and said, “To your offspring I will give this land.”
In chapter 15, God came to reassure Abram that He had not forgotten His covenant. “But Abram said, ‘O Lord Yahweh, what will you give me, for I continue childless, and the heir of my house is Eliezer of Damascus?’” Again God told Abram, “This man shall not be your heir; your very own son shall be your heir.” And He confirmed it with Abram by cutting the animals and renewing His covenant.
It had been nearly eleven years since Abram left Haran and he still did not have a son. So, Sarai gave him Hagar, her servant, and she bore Ishmael. Another thirteen years later, Abram was ninety-nine when God came again and gave him circumcision as a sign and seal of the covenant. The old man Abram was cut off, and the new man Abraham was raised up. When the flesh was cut away and the power of the flesh was spent, then Abraham was ready to father the child of promise. He still put forth Ishmael as his heir, but God said, “No, but Sarah your wife shall bear you a son, and you shall call his name Isaac. I will establish my covenant with him as an everlasting covenant for his offspring after him.”
So when God called Abraham to offer Isaac, his “only son,” the promise had been confirmed many times, so that Isaac was without doubt the intended heir. Abraham trusted in the resurrection of Isaac, as the writer of Hebrews says, “He considered that God was able even to raise him from the dead, from which, figuratively speaking, he did receive him back.” It is this trust in God and the hope of the resurrection that made Abraham able to carry out what God had commanded.