Abraham, going up to the mountain of sacrifice, together with Isaac knew that he has to offer his son. It is what is called human sacrifice, sometimes practiced in early primitive religion. There was a need to establish the truth about God, Yahweh, in is life and therefore God himself put him to the test, an absurd test.
With the promise that God will make his descendants as many as the stars and having only one legitimate son, Isaac, this same God, asked him to offer his son as a living sacrifice. Abraham, deep in his heart feels the pain of loosing a son for the sake of this self-proclaimed God whom he did not even knew totally. It is only by faith that he follows this calling.
Isaac however, has no idea of what is going on till a certain point that he was looking for he victim. With all the evidence around him, he finally understood that he will be the victim. Surprisingly he succumb to the idea and, if I am not mistaken, offered no resistance. But deep inside, we could enter into the helplessness of Isaac, and even doubt that Yahweh is the true God. How would a God believed by his father Abraham be such a cruel one?
He could have felt a certain abandonment, especially that of his own father. He is being sacrificed like a pawn. The love of his father is lesser that the love to a Being whom he does not even know. Anger, frustration, mixed with blind trust could have been inside his heart. Certainly, we could ask: Was he not abandoned by his father?
Here we enter into a paradox. In as much as Isaac feels this abandonment by his father Abraham, the very same father feels at the same time the suffering of offering his son. In as much as Isaac feels that his father is not in his side and leaves him alone to the point of death, Abraham at the same time, who loves his son dearly, suffers pain in an even more degree. In as much as Isaac is in darkness, Abraham his father, knows perfectly well what his son is undergoing and is closest to him.
We could understand a little the similar experience when Jesus the only son of God, nailed of the cross, dying, cried out: "My God, my God why have you forsaken me?" The father in heaven, in a certain sense is closest to His only son, when precisely His only Son feels the abandonment.
God is our loving Father. When we have to grow, and make decisions as if on our own, and we feel abandoned by our heavenly Father, like in the case of Isaac and Jesus, since we are all sons in the Son, Jesus, our Father in heaven, in those times and occasions, is precisely closest to us.