Well if surveys are to believed the predominant view in the US is that morality is dictated by God. I'm skeptical, but also, I have met people like that.

I think the argument for not committing violence when you are able to do so without any form of repercussion comes down to a morality issue, you don't do it because it is wrong. That works at an individual level, At a societal level you cannot assume all people to be moral. When faced with the inevitability of not all people being moral (or not agree on the same set of morals) you need a secondary reason to prevent violence. I suspect quite a lot of people would accept the morality of violence to prevent more violence. That is where individual morality might weigh in on the aspect of whether violence is appropriate to establish or protect the rule of law.