Psalms 1:6

"For the Lord knoweth the way of the righteous" (ver. 6). As it is said, medicine knows health, but knows not disease, and yet disease is recognised by the art of medicine. In like manner can it be said that "the Lord knoweth the way of the righteous," but the way of the ungodly He knoweth not. Not that the Lord is ignorant of anything, and yet He says to sinners, "I never knew you." "But the way of the ungodly shall perish;" is the same as if it were said, the way of the ungodly the Lord knoweth not. But it is expressed more plainly that this should be not to be known of the Lord, namely, to "perish;" and this to be known of the Lord, namely, to "abide;" so as that to be should appertain to the knowledge of God, but to His not knowing not to be. For the Lord saith, "I Am that I Am," and, "I Am hath sent me."

God is ignorant of evil deeds, not because he is unable to understand everything or to grasp it with his own intelligence (for it is wrong to think this way about God) but because those deeds are unworthy of his contemplation.… God is ignorant of the way of the wicked, and he knows the way of the righteous. Further, who is the way of the righteous except the one who said, "I am the way" whom the Father knows? "No one has known the Son except the Father." The distinction between the knowledge and ignorance of God is referred to in the prophets as "the memory and forgetfulness" of God. Often it is said in prayer: "Be mindful of me" and "Why have you forgotten our poverty?" Just as God removes sinners from his own memory, so does he again receive the repentant and become mindful of them.

It is precisely the scheme and system thus laid down in the Gospel that the Prophet has followed, when he says: Therefore the ungodly shall not rise again in the Judgement, nor sinners in the counsel of the righteous. He leaves no judgment for the ungodly, because they have been judged already; on the other hand, he has refused to sinners, who as we showed in our former discourse are to be distinguished from the ungodly, the counsel of the righteous, because they are to be judged. For ungodliness causes the former to be judged beforehand, but sin keeps the latter to be judged hereafter. Thus ungodliness having already been judged is not admitted to the judgment of sinners, while again sinners, who, are yet to be judged, are deemed unworthy of enjoying the counsel of the righteous, who will not be judged. The source of this distinction lies in the following words: For the Lord knows the way of the righteous, but the way of the ungodly shall perish. Sinners do not come near the counsel of the righteous for this reason, that the Lord knows the way of the righteous. Now He knows, not by an advance from ignorance to knowledge, but because He condescends to know. For there is no play of human emotions in God that He should know or not know anything. […]

For the Lord knows the way of the just, and the way of the ungodly shall perish. For the Lord knows the way of the just. And what is so great, if the Lord knows the way of the just? But God is said to know those whom he deigns to know. Indeed it is said of sinners: 'Depart from me, workers of iniquity, I do not know you.' The apostle says: 'If anyone knows, he is known.' For the Lord knows the way of the just. He who is a sinner, the Lord does not know him; he who is just, is known by God. We read in Genesis, at the time when Adam transgressed, at the time when he listened more to the serpent than to God, when he hid himself from the face of God, God came after the meal into paradise, and was walking about. See what is said. God seeks Adam, not at midday, but toward evening; for now Adam had lost the sun, because he had no midday. Toward evening, that is δείλινον, evening (deilinon), and he was walking. For God does not stand still for the sinner, but walks. For he knew that he was in paradise, and he was not ignorant of what had been done; but because Adam had sinned, God does not know him. And God said: Adam, where are you? We have spoken of this, how the sinner is not known by God: on the contrary we ought to know how the just man is known by God. God says to Abraham: 'Go forth from your land and from your kindred.' He came into Palestine, was in Abramium, was in Gerara a long time. When a son, Isaac, had been born to him, and he had received the promise 'That in your seed all the nations shall be blessed,' he took Isaac, and offered him to God, and a voice from heaven was heard, Spare your son. And immediately it is written there, at the time when he had offered his son, what does God say to Abraham? 'Now I have known that you fear the Lord your God.' You who had spoken for so long a time, have you now come to know Abraham? […]

(Verse 6.) It follows: For the Lord knows the way of the righteous, and the way of the wicked shall perish. Pay attention to the meaning: The wicked do not rise in judgment, for the Lord knows the way of the righteous. Certainly He knows their ways, whose steps are directed by the Lord. They are the steps of men who are guided by the Lord. They are guided by the Lord and the ways of man.