12 And he said, Lay not thine hand upon the lad, neither do thou any thing unto him: for now I know that thou fearest God, seeing thou hast not withheld thy son, thine only son from me.
In this statement it is usually thrown out against us that God says that “now” he had learned that Abraham fears God, as though he were such as not to have known previously. God knew, and it was not hidden from him, since it is he “who has known all things before they come to pass.” But these things are written on account of you, because you too indeed have believed in God. But unless you fulfill “the works of faith,” unless you are obedient to all the commands, even the more difficult ones, unless you offer sacrifice and show that you place neither father nor mother nor sons before God, you will not know that you fear God. Nor will it be said of you, “Now I know that you fear God.”And yet it must be considered that an angel is related to have spoken these words to Abraham, and subsequently this angel is clearly shown to be the Lord. Whence I think that, just as among us “he was found in appearance as a man,” so also among angels he was found in appearance as an angel. And following his example the angels in heaven rejoice “over one sinner repenting” and glory in the progress people make in their relationship with God. For they, as it were, have charge over our souls, to whom, “while we are still children we are committed,” as it were, “to tutors and governors until the time appointed by the father.” And they therefore now say about the progress of each of us, “Now I know that you fear God.” For example, I intend to be a martyr. An angel could not say to me on this basis, “Now I know that you fear God,” for an intention of the mind is known to God alone. But if I shall undertake the struggles, if I shall utter a “good confession,” if I shall bear calmly all things which are inflicted, then an angel can say, as if confirming and strengthening me, “Now I know that you fear God.”
But grant that these words are spoken to Abraham, and he is said to fear God. Why? Because he did not spare his son. But let us compare these words with those of the apostle, where he says of God: “who spared not his own Son but delivered him up for us all.” Behold God contending with people in magnificent generosity: Abraham offered God a mortal son who was not put to death; God delivered to death an immortal Son for humanity.What shall we say to these things? “What shall we render to the Lord for all the things that he has rendered to us?” God the Father, on account of us, “spared not his own son.” Who of you, do you suppose, will sometime hear the voice of an angel saying, “Now I know that you fear God, because you spared not your son,” or your daughter or wife? Or, you spared not your money or the honors of the world or the ambitions of the world, but you have despised all things and “have counted all things dung that you may gain Christ”? Or, “you have sold all things and have given to the poor and have followed the Word of God?” Who of you, do you think, will hear a word of this kind from the angels? Meanwhile Abraham hears this voice, and it is said to him, “You spared not your beloved son because of me.”
Hence we are not permitted to doubt that the knowledge of God is adapted to the time rather than to the result of a change, since in connection with that which God knew it is a question of the opportune moment to divulge what is known rather than to acquire it. [This] we are also taught by the words that were spoken to Abraham: “Do not lay your hand on the boy, and do nothing to him, for I know now that you fear your God, and have not spared your beloved son for my sake.” Accordingly, God knows now, but to know something now is an admission of previous ignorance. Since it is a contradiction for God not to know that Abraham had been previously faithful to him and of whom it had been said, “Abraham believed God, and it was credited to him as justice,” that which he knew at this moment is the time when Abraham received this testimony, and not the time when God also began to acquire this knowledge. By bringing his son as a holocaust, Abraham manifested the love that he had for God. God was aware of it then when he speaks. And, since we are not to believe that he had been ignorant of it up to that moment, we must understand that he knew of it then because he speaks of it. Of the many passages in the Old Testament that contain references to the knowledge of God, we have cited only this one as an example that we may realize that God’s ignorance of anything does not arise from a lack of knowledge but from the occasion.
He showed the ram in the thicket in the stead of the lad, that He might restore the son to his father, and yet the victim not fail the priest. And so Abraham was not stained with his son's blood, nor was God deprived of the sacrifice. The prophet spoke, and neither yielded to boastfulness nor continued obstinate, but took the ram in exchange for the lad. And by this is shown the more how piously he offered him whom he now so gladly received back.
Determined by motives of high devotion, Abraham, obeying the oracle of God, offered his son for a whole burnt sacrifice; and, as if destitute of natural affection, drew his sword, that no delay might obscure the brightness of the offering. But when he was commanded to spare his son he willingly sheathed his sword, and he who with this faithful intention was hastening to offer up his only son with still more zealous piety hastened to substitute a ram as a sacrifice.
We have heard enough on how God does not know the sinner, so we ought to consider now how the just man is known by him. God said to Abraham, “Leave your country, your kinsfolk.” Abraham accordingly came into Palestine; he was in Abramiri; he sojourned a long time in Gerar. When his son Isaac was born, he had received the promise: “In your descendants all the nations of the earth shall be blessed.” He took Isaac and offered him to God, and a voice from heaven was heard to say, Spare him. Straightway, at the very moment that he offered his son, what does God say to Abraham? “I know now that you fear the Lord, your God.” Have you just now known Abraham, Lord, with whom you have communicated for such a long time? Because Abraham had such great faith in sacrificing his own son, on that account God first began to know him. Why have we said all this? Because it is written, “For the Lord knows the way of the just.” Let us put it another way: The way, the life, and the truth is Christ; let us walk therefore in Christ, and then God the Father will know our way.
He also said, ‘The beginning and the end is the fear of the Lord. For it is written, “The fear of the Lord is the beginning of wisdom” (Ps. 111:10) and, when Abraham built an altar the Lord said to him, “Now I know that you fear God” (Gen. 22:12).’
In the same way he said to Abraham, “Now I know that you fear God,” wherein he was saying, “Now I have made people (who up to now did not know) recognize what I, in my own mind, always held to be certain, [namely], that you fear God.”
[AD 253] Origen of Alexandria on Genesis 22:12