I think Abraham knew, and I think the context of the passage bears that out. One thing that stands out from the rip for me is that Abraham was praised as being righteous not for obedience, but for faith.
Discussion
10 Then Abraham reached out his hand and took the knife to slaughter his son. 11 But the angel of the Lord called to him from heaven and said, “Abraham, Abraham!” And he said, “Here I am.” 12 He said, “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 think the plain reading of the text is clear. I think it’s human to put effort into explaining away the messy implications than directly wrestling with them. But I think it’s worth wrestling with. Kierkegaard’s “Fear and Trembling” is worth it in my opinion.
There is more to be said but I’ll leave it short. GM