Be careful who you claim to speak for. Who you claim to represent. Whose pain you claim to want to salve. Before you tear down a wall on behalf of someone else, make sure it's not one of the walls of their fucking house.
Wipe every iota of vengeance from your principles, your slogans, your actions. Background-check your prophets and priests.
Make sure your words are your own, and not the approved keywords of your group. Read the books of those who you abhor.
See that you have done, in a great, long silence, a thorough check for the plank in your own eye before you go hunting for specks in your neighbor's. Or your nation's.
Until you have done so, do not dare to speak on someone else's behalf. Otherwise, you are the very worst kind of pimp.
A message from Dave.