In order that no one may suppose that, whereas he speaks of old and new, he is introducing a different person, observe his expression, “That ye be renewed.” To be renewed is, when the selfsame thing which has grown old is renewed, changed from one thing into the other. So that the subject indeed is the same, but the change is in that which is accidental. Just as the body indeed is the same, and the change in that which is accidental, so is it here. How then is the renewal to take place? “In the spirit of your mind,” says he. Whosoever therefore has the Spirit, will perform no old deed, for the Spirit will not endure old deeds. “In the spirit,” says he, “of your mind,” that is, in the spirit which is in your mind.
Ver. 24. “And put on the new man.”
Do you see that the subject is one, but the clothing is twofold, that which is put off, and that which is put on? “The new man,” he continues, “which after God has been created in righteousness and holiness of truth.” Now wherefore does he call virtue a man? And wherefore vice, a man? Because a man cannot be shown without acting; so that these things, no less than nature, show a man, whether he be good or evil. Now as to undress one's self and to dress one's self is easy, so may we see it is with virtue and vice. The young man is strong; wherefore let us also become strong for the performance of good actions. The young man has no wrinkle, therefore neither should we have. The young man wavers not, nor is he easily taken with diseases, therefore neither should we be.
Observe here how he calls this realizing of virtue, this bringing of it into being from nothing, a “creation.” But what? Was not that other former creation after God? No, in no-wise, but after the devil. He is the sole creator of sin.
How is this? For man is created henceforth, not of water, nor of earth, but “in righteousness and holiness of truth.” What is this? He straightway created him, he means, to be a son: for this takes place from Baptism. This it is which is the reality, “in righteousness and holiness of truth.” There was of old a righteousness, there was likewise a holiness with the Jews. Yet was that righteousness not in truth, but in figure. For the being clean in body was a type of purity, not the truth of purity; was a type of righteousness, not the truth of righteousness. “In righteousness,” says he, “and holiness,” which are “of truth.”
And this expression is used with reference to falsehood; for many there are, who to them that are without, seem to be righteous, yet are false. Now by righteousness is meant universal virtue. For hearken to Christ, how He says, “Unless your righteousness shall exceed the righteousness of the scribes and Pharisees, you shall in nowise enter into the kingdom of heaven.” And again, he is called righteous, who has no charge against him; for so even in courts of justice we say that that man is righteous, who has been unrighteously treated, and has not done unrighteously in return. If therefore we also before the terrible Tribunal shall be able to appear righteous one towards another, we may meet with some lovingkindness. Toward God indeed it is impossible we should appear so, whatever we may have to show. For everywhere He overcomes in what is righteous, as the Prophet also says, “That You might prevail when You come into judgment.” But if we violate not what is righteous towards each other, then shall we be righteous. If we shall be able to show that we have been treated unrighteously, then shall we be righteous.
How does he say to them who are already clothed, “put on”? He is now speaking of that clothing which is from life and good works. Before, the clothing was from Baptism, whereas now it is from the daily life and from works; no longer “after the lusts of deceit,” but “after God.” But what means the word “holy”? It is that which is pure, that which is due; hence also we use the word of the last duty in the case of the departed, as much as to say, “I owe them nothing further, I have nothing else to answer for.” Thus it is usual for us to say, “I have acquitted myself of all obligations,” and the like, meaning, “I owe nothing more.”
Moral. Our part then is, never to put off the garment of righteousness, which also the Prophet calls, “the garment of salvation”, that so we may be made like God. For He indeed has put on righteousness. This garment let us put on. Now the word, “put on,” plainly declares nothing else, than that we should never at all put it off. For hear the Prophet, where he says, “He clothed himself also with cursing as with his garment, and it came into his inward parts.” And again, “Who coverest Yourself with light as with a garment.” And again, it is usual with us to speak concerning men, such an one has “put on” such an one. So then it is not for one day, nor for two, nor for three, but he would have us ever arrayed in virtue, and never stripped of this garment. For a man is not so disfigured when he is stripped of his clothing, as when he is stripped of his virtue. In the former case his fellow-servants behold his nakedness, in the latter his Lord and the Angels. If ever thou happen to see any one going out naked through the public square, tell me, are you not distressed? When then you go about stripped of this garment, what shall we say? Seest not those beggars whom we are wont to call strollers, how they roam about, how we pity even them? And yet nevertheless they are without excuse. We do not excuse them when they have lost their clothes by gaming; and how then, if we lose this garment, shall God pardon us? For whenever the devil sees a man stripped of his virtue, he straightway disguises and disfigures his face, and wounds him, and drives him to great straits.
Source: Homilies on Ephesians (New Advent)