For Buddhists, hatred is one of the Three Poisons: greed, hatred and delusion. These poisons manifest in thoughts, intentions, and actions that cause suffering for self and others. The poisons arise out of the natural proclivity of humans to desire things, reject things and grasp and cling to phenomena thought to bring happiness (as well as out of the proclivity to reject what is thought to bring unhappiness.)
Here’s a grossly oversimplified example of how it works: Money is erroneously thought to bring happiness; a profit-driven company will not give you a raise; you hate the company for denying you what you desire. If the desire/hate is strong enough, the poison may manifest in violence.
Buddhists believe our tendency towards desiring some things and rejecting others is fully human but grounded in a sort of ignorance of the way life actually works. There is nothing—literally nothing—in the world that will satisfy your natural desires in a lasting way. In the example above, money will not bring happiness. Continuing to seek that which does not exist is a futile, ignorant quest. The only way to gain peace and contentment is to accept the basic facts of existence: everything changes or fades. It is our nature to get old, get sick, and die. Grasping and clinging result in suffering. And the sense of a fixed, permanent self is useful but inaccurate.
Coming to fully realize these facts is a move from ignorance to awakening, and once awakened, the three poisons are expelled.
A grounded Buddhist, then, would look on acts of hatred and attempt to see through the surface and recognize the fundamental ignorance of the hater. Recognizing the Three Poisons flow in the veins of all—to one degree or another—seeing the ignorance of the hater calls to mind one’s personal ignorance.
This recognition may allow compassion to arise; not acceptance of the deeds of the hater, but compassion for the pain and suffering experienced by the hater and the victims of the hate. In addition—given that ignorance may be dispelled—a grounded Buddhist may offer up well-wishes of lovingkindness to the hater. These wishes are called metta. There are many variations, but a truncated version goes like this:
To the hater…
May you be happy.
May you be well.
May you not suffer.
May you experience joy.
May you have wisdom