Anger
Anger is one of the passions of the soul. It proceeds from a real or imaginary offense which makes us want to "get even" with the offender. When the desire for revenge is not suppressed, it is a sin and a vice. It is opposed to charity and justice. Every kind of anger, however, is not a vice. As occasional fit of temper is not the vice of anger, but it may be a sin. There is also a form of anger that is good and virtuous, when it proceeds from a proper cause, as in the case of Our Lord driving the buyers and sellers from the Temple.
We have given way to anger and hate when we harbor resentment in our heart against a certain person or persons; when we plot harm for anyone by word or deed; when we use insulting language toward the offender. We are guilty of anger when we become excited and incenses to such a degree that we strike or hurt another; when we wrangle and quarrel violently with another; or when by the sullen expression on our face or by our silence, we show our resentment toward him. Our sin is very, very serious if we harbor rancor or hatred in our heart for days, or months, or even years and abstain from marks of kindness and friendship. We are also guilty of anger if we abuse our authority and punish as inferior more than he deserves. We may even direct our anger toward God interiorly, or exteriorly in passionate blasphemy.
Anger is a destructive and highly injurious vice. A fit of rage deprives us of reason; it estranges us from God. It separates us from friends and relatives. Anger clouds the intellect, and its unreasoning obstinacy makes us trample on the rights of others.
Anger destroys peace and produces disastrous wars. It causes all sorts of evils, discords, enmities, long-standing quarrels, insults, spites, slander, blasphemy, hatred revenge, murder. All these things kill charity and are obstacles to grace, our greatest gift from God.