There is anger which is not sinful...and a man may be said to be angry and not sin, when his anger arises from a true zeal for God and religion; when it is kindled not against persons, but sins; when a man is displeased with his own sins, and with the sins of others: with vice and immorality of every kind; with idolatry and idolatrous worship, and with all false doctrine; and also when it is carried on to answer good ends, as the good of those with whom we are angry, the glory of God, and the promoting of the interest of Christ: and there is an anger which is sinful; as when it is without a cause; when it exceeds due bounds; when it is not directed to a good end; when it is productive of bad effects, either in words or actions; and when it is soon raised, or long continues..."
- excerpt from John Gill's Bible commentary on Ephesians 4:26