Being humans mean having the capacity to empatize with the other, even when the other is doing something so inhumane, you get sick. But inhumane behaviours of other people do not justify our inhumane behaviours.
Being humans mean the ability to not respond to negativity with more negativity, without being passive and complacent. We want to improve life as we live it and in doing so, we want to reduce negativity by promoting more positivity into the world.
That, in itself, is not a sign of weakness on our part. When someone punches you and you punches him back, that is actually weakness because you have succumbed to your base desire to get even and not your higher ideals to make the situation better.
This does not mean that the person who punches you should walk away scotch free. Promoting positivity does not mean that we overlook justice. In fact, it doesn’t make sense to promote positivity without promoting justice at the same time.
The thing is, under normal circumstances, justice doesn’t have to be upheld with violence. Those who resort to violence immediately are obeying their animalistic urges. The more animalistic you become, the less human you are.