When something needs to be done in the world to rectify the wrongs, if one is really concerned with benefiting others, one needs to be engaged, involved. This is action out of compassion.
The indifference, callousness and contempt that so many people exhibit toward animals is evil first because it results in great suffering in animals, and second because it results in an incalculably great impoverishment of the human spirit.
The perspective of Love doesn't leave anybody out. Until your vision and compassion is big enough to include those who oppose you, you are simply contributing to the continuation of destructiveness . The end of separation is the salvation for all.
If you resort to violent methods because the other side has destroyed your monastery, for example, you then have lost not only your monastery, but also your special Buddhist practices of detachment, love, and compassion.