Hate is good. At least to the extent that it opposes evil. And there lies the challenge: to differentiate between what is evil and what is not. Let's all take a moment to set our moral compasses:

Golden retriever puppies: not evil.
Constantly reminding others of your past accomplishments: evil.

A mother's unconditional love for her child: not evil.
Casting off a legendary player to a dismal franchise after years of greatness: evil.

Cold beer on a hot day: not evil.
Two fat guys celebrating by dumping beer onto a statue of that same legendary player, hours after one failed miserably on the mound and a week before the other would awe the world with a 1-inning outing: evil. And pathetic.

Effectively opposing evil takes a lot of energy, and "hate" simply reflects the requisite level of energy. So, again, hate is good. When the hate of many is bundled together, an immense energy force can be achieved. This force can be concentrated in a single location-like a baseball stadium-or dispersed across a nation. In either case, the force is powerfully present. The Evil Empire feels it. Thinks about it. Becomes distracted by it.

And, in the end, is destroyed by it.