“Whoever is slow to anger is better than the mighty, and he who rules his spirit than he who takes a city.” (Proverbs 16:32)
Incredibly, Christ’s commentary on the sixth commandment includes a person’s inner state. Anger is subject to God’s judgment (Matt. 5:22). This was not original with Jesus. Moses had already recorded God’s will, “You shall not hate your brother in your heart . . . or bear any grudge against the sons of your own people, but you shall love your neighbor as yourself “ (Lev. 19:17-18). Lack of love, as well as positive hatred, is a form of murder.
Anger is not always wrong. If it were, God would be the chief sinner, for he is angry every day (Ps. 7:11). And note that David does not say God is angry merely at sin. He is angry with wicked people.1 The wrath of God is seen throughout the Old and New Testaments and is the inevitable result of his holy character exposed to unholy attitudes and behavior.
But is it possible for a sinful mortal to be godlike in his anger? It must not be easy, for the Bible is filled with teaching against anger. Anger is to be put away (Eph. 4:31; Col. 3:8); whoever is angry is in danger of judgment (Matt. 5:22); anger is one of the works of the flesh (Gal. 5:19-20); it does not work the righteousness of God (James 1:20); and it is the prerogative of God, not man (Rom. 12:19). Proverbs condemns anger repeatedly.
But Jesus was angry (Mark 3:5), and we are commanded in our anger to refrain from sin (Ps. 4:4; Eph. 4:26), to be slow about it (Titus 1:7; James 1:19), and to get over it quickly (Eph. 4:26). There seems to be approval of being angry under some circumstances, but the major biblical emphasis is on anger as evil; exceptions seem very limited.
Anger at sin, even anger at the sinner, can be a good thing (1 Cor. 7:11). Jeremiah was full of the fury of the Lord (6:11), and Paul was angry over the idolatry of the Athenians (Acts 17:16). Yet Christ himself refrained from anger when the offense was against him personally (1 Pet. 2:23-24), and “like a sheep that before its shearers is dumb, so he opened not his mouth” (Isa. 53:7).
Righteous and unrighteous anger can be distinguished by the cause of anger. One should be angry over sin that offends God, harms others, or harms the person sinning. The difficulty with being righteously indignant is that our motives are mixed. Am I distressed over a sin that offends God and harms people, or am I angry over the way I am affected? Since motives are mixed, the safe thing may be to eschew anger altogether when the sin of another directly affects me, as when my child does wrong but the wrong embarrasses me. Better to wait till the anger subsides to be sure the resulting action does not come from a mixture of righteous and unrighteous indignation. Anger is sinful when it is for the wrong reason or results in the wrong action.
Some say that God’s anger is merely judicial—he takes a position of judgment against sin. The theory is that God’s wrath is impersonal and objective and without any emotion of indignation on his part. But this is not the biblical picture of a God who burns with fury. Judging by the reaction of Jesus to sin against himself, this fury is over what sin does to the sinner and those he sins against rather than over what sin does to God himself. But God’s example does imply that some people, if they were filled with the Spirit, would become angry, possibly for the first time. In an age when “there is no sin but the sin of intolerance,” some of us need to be stirred to participate with an angry God against the wickedness, oppression, and evil of this world.
To keep this emotion from igniting for the wrong reason or from burning out of control, Scripture gives two ways of control: Take it easy—don’t get angry suddenly (James 1:19), and don’t let it keep burning—don’t let it last till the next day (Eph. 4:26). Either a “low flashpoint,” a quick response without reflection, or a “slow burn,” continuing on with the emotion, seem to risk causing even righteous indignation to go astray.
Against the clear teaching of Scripture that most (not all) human anger is wrong, and that the proper response is to control it (Prov. 16:32), many Christian psychologists hold that anger is morally neutral and must be expressed.2 To this we respond that anger is neutral in the same way that hatred and killing are neutral: Sometimes they are right; mostly they are wrong. Anger in itself is a wrong emotion to have if it is directed against the wrong object (God, an innocent person, a thing); for the wrong cause (personal offense); or leads to wrong behavior (retaliation, vengeance, physical violence).
Anger under these circumstances should not be denied or expressed. It should rather be confessed as sin and the resources of God appropriated to control the emotion itself.
Lloyd H. Steffen, writing “On Anger,” indicates that anger is not always bad: “Sometimes only anger will make us act to address a grievance or change a situation.” But, addressing the position common among psychologists that anger must be ventilated, he responds:
Ventilating anger is like ventilating a fire. The environment will only become more heated and smoky, the damage will only increase. Ventilating anger postpones investigation of its causes and the beginning of repairs. . . . Our anger is usually a response to things that we perceive as somehow injuring us, or that keep us from having our own way.
To encourage a person who feels guilty about his anger by assuring him that there is nothing wrong with this perfectly human reaction, and that the only healthful thing is to express the anger and not feel guilty, will simply drive the sensitive Christian’s real guilt “underground” and put off the day of biblical resolution. Rather, the person needs to be encouraged to evaluate in the light of Scripture whether his anger is godly and, if it is not, to confess his sin, thus removing all guilt. Then he should trust God for his resources in overcoming the temptation. 
 Lloyd H. Steffen, “On Anger,” The Christian Century, 16 January 1985, 47.
 IBE (2014) , 354-344.