“Be Angry And Sin Not” - On Ephesians 4:26

St. Thomas Aquinas, Commentary on Ephesians 4:26: “He gives his warning when he says ‘Be angry, and sin not’ [Eph. 4:26]. This is susceptible of two interpretations; for there are two types of anger, a good one and an evil one. Anger is evil when, contrary to justice, it strives inordinately for revenge. It is good when it seeks a just vindication, namely, when the person is vexed at the time, with whom, and to the degree that, he should be… If it is interpreted concerning righteous anger it is not simply permitted, like the first, but imperative…
     Now, some are doubtless of the opinion that a man can be mad at himself for his own sins safely, but that this does not hold true concerning his neighbors and their sins. This is false; a man can be mad at himself for his own sins, and at his fellow man because of his sins. Therefore, zealously be angry at other people’s offenses. ‘Phinees hath turned away my wrath from the children of Israel because he was moved with my zeal against them’ (Num. 25:11). And Elias said: ‘With zeal have I been zealous for the Lord God of Hosts: for the children of Israel have forsaken thy covenant’ (3 Kg. 19:10). By following the dictates of reason, rather than acting before [reason has had time to reflect], you sin not. ‘Let every man be swift to hear, but slow to speak, and slow to anger’ (Jas. 1:19).”