We cannot have a country worth living in, or at all, unless people who disagree resolve their differences peacefully.
I assume that we all here are non-pacifists, right? That means that while we generally prefer peace to war, we don't accept that as an absolute. War was better than letting Hitler take over Great Britain, or, less obviously, than letting Hitler take over the USSR (if only for the geostrategic considerations).
Similarly, the assumption of living in a civil society is that violence should be primarily left to the government. However, it is not entirely so: I know of no political subdivisions in the US that deny the right to self-defense, and frankly, any that did I would consider tyrannical. The Second Amendment was written with the intent of giving individuals the right to their own defense. In fact, many of the Founders appear to have actually considered a militia consisting of all able-bodied males to be preferable to a standing army! Furthermore, it's pretty obvious, both from the mere fact of the American Revolution and from the writings of the Founders, that they did not consider violence against a tyrannical government beyond the pale.