Hate is the combination of fear and sadness.
While sadness brings on a feeling of weakness and vulnerability, fear creates paranoia. The combination of the two can turn extreme which creates defensive behavior.
In order to defend themselves, many choose to attack. Hate is the energy behind every attack. Externally, this can be in the form of physical violence. Internally, this can be in the form of judgments.
To hate requires the same amount of energy as to love. Anything that lacks love in the physical, develops the ability to numb feelings. This opens the possibility of creating a heavy darkness in the place of love.