The following comes from the Catholic Exchange:
Jesus often spoke about the obligation of fraternal charity. He took us beyond the prohibition of killing or even striking a brother. He said that we must not become angry with our brother, nor show our bitterness toward him by injuring him in any way.
If we have a dispute, we must be easily reconciled, must not seek to bring our disagreement to an end by taking it before a judge, nor even seek a mediator to heal our division. For Christ is the mediator of our reconciliation, and it is the spirit of his charity and grace that should animate us. We ought to be willing to bend, so that, together with our brother, we can be mutually accommodating.
He said that if we come to sense some bitterness in our brother’s heart, we must take care to appease him and to prefer reconciliation to sacrifice. But he pushes the obligation still further and uproots the spirit of vengeance. “An eye for an eye and a tooth for a tooth” (cf. Exod. 21:24). This is what was permitted of old, and it seems to be a certain kind of justice. But Jesus does not allow a Christian either to do it himself or to seek satisfaction in this way. If the public authority punishes crimes, the Christian does not prevent it; he respects public order. But for his part, far from avenging himself upon the one who strikes him, he turns the other cheek; he would rather give his coat to the one who would steal his shirt than to seek legal redress for such a small matter and thus burden his mind with legalism and resentment (Matt. 5:39-40). He will more willingly walk two miles with someone who would force him to walk one than seek justice for himself or even dream of causing harm to one who had hurt him. The tranquillity of his heart is more dear to him than the possession of anything that injustice could take away, and if a breach of charity were required to recover something that had been taken away from him, he would not want it at any price.
O gospel, how pure you are! O teaching of Christ, how worthy of our love you are! Yet alas, how poorly we Christians respond to it, and how little worthy are we of so lovely a name!
“Give to him who begs from you, and do not refuse” — as is so often done — “him who would borrow from you” (Matt. 5:42). Do what you can to care for those who suffer: be beneficent. The sum of the world’s riches does not equal the price of these two virtues, nor the reward that they will gain us.
Here then are the three degrees of charity toward our enemies: to love them, to do good to them, and to pray for them. The first is the source of the second: if we love, we give. The last is the one that we think is the easiest to do, but is in fact the most difficult, because it is the one that we must do in relation to God. Nothing should be more sincere, nothing more heartfelt, nothing truer than what we present to the one who sees all, even into the depths of our heart.
Let us examine these three degrees: to love, to do good, and to pray. What is it to “love those who love you”? “Do not even the tax collectors do the same? . . . Do not even the Gentiles do the same?” (Matt. 5:46-47). It is not for nothing that you are offered an eternal inheritance and an unchanging happiness: it is not to leave you indifferent, or worse than pagans.