"Hatred ceaseth not by hatred," declared the Buddha, "It ceaseth only by compassionate love." This counsel is much the same as Jesus' injunction to love our enemies. Many people, who wish to do what is ethically right and feel that their best course is to follow the ethics prescribed by such great souls as Jesus or Buddha, get confused here and wallow in sentimentality under the mistaken impression that they are following these counsels.
But the sentimentalists misunderstand Jesus if they believe that he taught us to practise outwardly and practically unconditional and universal forgiveness. On the contrary, he made repentance the prerequisite of such visible forgiveness. Those who refuse to repent and persist in wrongdoing must be inwardly and silently forgiven, but otherwise left to suffer the karma of their actions. What is really meant is that we should be big-hearted enough not to exclude our enemies from our goodwill to all mankind and that we should be big-minded enough to comprehend that they are only acting according to their own experience and knowledge of life. This is to "forgive them for they know not what they do." When we hold them in thought and when we image them with feeling we must do so without anger, without hatred, without bitterness.
All doctrines which are based on hatred emanate from the blackest of evil forces. Hatred is always their indicator just as compassion is always an indicator of the good forces. By practising great-hearted compassion, we help to counteract whatever ill-feelings have been generated. Therefore let us not at any time or under any provocation lose ourselves in emotions of resentment, bitterness, and hatred. We must not hate the most misguided of our enemies. We may oppose their false ideas resolutely, we may hate their sins, but not the sinners. We must pity even the most violent of them and not spoil our own characters by accepting their example. We must not sink to the low level of seeking revenge. The desire for revenge is a primitive one. It is apposite to the tiger and reptile kingdom, but in the human kingdom it should be replaced by the desire for justice.
These two attributes--hatred and pity--stand at opposite poles to each other: the one as being the worst of all human vices and the other as being the best of all human virtues. This, then, is a further reason why we must take care not to fall into the all-too-easy habit of hating enemies. For they are still members of this great human family of ours, still creatures planted like us on this woeful planet both to learn its immediate lessons and to share its ultimate redemption.
-- Notebooks Category 6: Emotions and Ethics > Chapter 2 : Re-Educate Feelings > # 136