Hate stems from the perception of being hurt or wronged. Hate, properly applied, has a positive purpose. Consider this passage from C.S. Lewis' Perelandra, in which Professor Ransom is wrestling with the Un-Man:
What was before him appeared no longer a creature of corrupted will. It was corruption itself to which will was attached only as an instrument. Ages ago it had been a Person: but the ruins of personality now survived in it only as weapons at the disposal of a furious self-exiled negation. It is perhaps difficult to understand why this filled Ransom not with horror but with a kind of joy. The joy came from finding at last what hatred was made for.Why would an almighty God allow such a thing as hatred...? Because it has exquisite, necessary utility. Love is the condition by which we care for others more than we care for ourselves. Unalloyed Love leads us to allow evil without opposition. We become the unwitting tools of evil. We become enablers. Hate, properly applied, motivates us to combat evil. In the presence of Love, Hate gives us the strength to act where we might otherwise consider only our own survival. It keeps us from being cowards.
Hate becomes a problem in the absence of Love.
Without Love... putting others first... we make ourselves the center of everything. Every matter of ethics and morality becomes relative and subjective. We focus only on the offense that we take, without considering whether offense was given. Thus, we are offended by everything and we hate freely. And because admitting to our hatred would damage our self-image, we cannot bring ourselves to do that. Instead, we justify our selfishness using the language of emotions we do not truly feel. Not necessarily toward everyone... but certainly toward those who don't bolster our self-image... those who are not useful to us.
Look around. Look inside. Judge for yourself.
To every thing there is a season, and a time to every purpose under the heaven.