Just because I don't support using violence as a "solution" does not mean I'm saying not do anything at all. There are other actions a person can take, such as signing petitions, boycotting, attending a peaceful protest, writing, emailing, and just spreading the word. These actions show people that you care. When you use violence as a solution, the general public does not see the cause in which the violence was committed for. What the general public sees are extremists who hurt people.
So, when violence is used, it overshadows the very cause you claim to care about. Violence will only beget more violence and it solves nothing. What you need is to appeal to people's compassion and empathy.