8 Now do not think that anger is nothing. “My eye was disordered because of anger,” says the Prophet. Surely he whose eye is disordered cannot see the sun; and if he should try to see it, it were pain, and no pleasure to him. And what is anger? The lust of vengeance. A man lusts to be avenged, and Christ is not yet avenged, the holy martyrs are not yet avenged. Still does the patience of God wait, that the enemies of Christ, the enemies of the martyrs, may be converted.
And who are we, that we should seek for vengeance? If God should seek it at our hands, where should we abide? He who has never in any matter done us harm, does not wish to avenge Himself of us; and do we seek to be avenged, who are almost daily offending God? Forgive therefore; from the heart forgive. If you are angry, yet sin not. “Be angry, and sin not.” Be angry as being but men, if so be you are overcome by it; yet sin not, so as to retain anger in your heart (for if you do retain it, you retain it against yourselves), lest ye enter not into that Light.
Therefore forgive. What then is anger? The lust of vengeance. And what is hatred? Inveterate anger. If anger become inveterate, it is then called hatred. And this he seems to acknowledge, who when he had said, “My eye is disordered because of anger;” added, “I have become inveterate among all mine enemies.” What was anger when it was new, became hatred when it was turned into long continuance. Anger is a “mote,” hatred, a “beam.” We sometimes find fault with one who is angry, yet we retain hatred in our own hearts; and so Christ says to us, “You see the mote in your brother's eye, and see not the beam in your own eye.” How grew the mote into a beam?
Because it was not at once plucked out. Because you suffered the sun to rise and go down so often upon your wrath, and made it inveterate, because you contracted evil suspicions, and watered the mote, and by watering hast nourished it, and by nourishing it, hast made it a beam. Tremble then at least when it is said, “Whosoever hates his brother is a murderer.” You have not drawn the sword, nor inflicted any bodily wound, nor by any blow killed another; the thought only of hatred is in your heart, and hereby are you held to be a murderer, guilty are you before the eyes of God.
The other man is alive, and yet you have killed him. As far as you are concerned, you have killed the man whom you hate. Reform then, and amend yourself. If scorpions or adders were in your houses, how would ye toil to purify them, that you might be able to dwell in safety? Yet are you angry, yea inveterate anger is in your hearts, and there grow so many hatreds, so many beams, so many scorpions, so many vipers, and will you not then purify the house of God, your heart? Do then what is said, “As we also forgive our debtors;” and so say securely, “Forgive us our debts.”
For without debts in this earth ye cannot live; but those great crimes which it is your blessing to have been forgiven in Baptism, and from which we ought to be ever free, are of one sort, and of another are those daily sins, without which a man cannot live in this world, by reason of which this daily prayer with its covenant and agreement is necessary; that as we say with all cheerfulness, “Forgive us our debts;” so we may say with all truth, “As we also forgive our debtors.” So much then have we said as touching past sins; what now for the future?
Source: Sermons on Selected Lessons of the New Testament (New Advent)