Violent fundamentalists are those who believe that the "rightness" of their cause justifies even the most heinous of crimes. They are right, and others have no rights. Whether "religious" and secular, down through the ages violent fundamentalists have been responsible for terrible atrocities--crusaders slaughtering Muslims, inquisitors torturing heretics, Nazis gassing Jews, communists annihilating counterrevolutionaries, capitalists tyrannizing the poor.
Or This:
A leftist's unyielding adherence to rigid doctrinal and ideological positions may find expression in his or her social and political, as well as religious, attitudes. Violent leftists are those who believe that the "rightness" of their cause justifies even the most heinous of crimes. They are right, and others have no rights. Whether "leftist" and secular, down through the ages violent leftists have been responsible for terrible atrocities--palestinians slaughtering Israelis, communists annihilating counterrevolutionaries, statists tyrannizing the poor.
Seems a better fit to me.