By acting as bullies they put the lie to the fundamental premises of pacifism. You cannot shame a bully who has no shame. Gandhi and MLK Jr. succeeded because some of their opponents had a modicum of shame. But you will notice that both of them were murdered, and the kinds of people who would do that will not be deterred by pacifism. It is a dogma, bordering on religious superstition that there is always a non-violent answer to every problem. The fact is that when someone comes at you with a gun to take your life that you will have to defend yourself or die. Most liberals are in serious denial about this. When your opponents constantly announce their desire to kill you, you cannot afford to just dismiss this all as idle talk. Yes, it's true that most bullies are chicken s**t little cowards who threaten because they are too impotent to act. However, threats do give the threatener power, especially if you never properly answer them or prepare for the worst case scenario. The proper answer to a threat is not to passive-aggressively ignore it, or use some namby-pamby platitude like, "I won't dignify that comment with a response". Remember, you are trying to shame people who may well have no sense of shame. The only intelligent, appropriate response to a threat is to counter the threat with your own promise of all legitimate responses against it immediately. When someone says, "liberals deserve to die" you need to immediately have that person prosecuted for hate speech, while at the same time, taking maximum effort to insure that you are prepared to meet this person's threat with lethal deterrence.
Most liberals don't own guns because they are that deep in denial. They will usually justify it by citing some vague "study" that says having a gun in the house is dangerous and could be used against you. Yeah, if you don't secure the gun. IOWs, if you act like an idiot about owning a gun then it certainly will be dangerous to you. If you're a colossal wussie and know that you will wimp out on pulling the trigger instead of seeing that assailant as a tree stump to be used for target practice, then you will become a victim of your own firearm, and I can't say I feel too sorry for you. You had your chance right in your hand and you refused to take it.
This is the same thing that left-wingers do politically all the time. For a long time these guys refused to fight back against an onslaught of negative attack ads. They said "they wouldn't lower themselves" to campaign that way and they lost and they are footnotes in history that are lower than whale poo. So much for not lowering yourselves.
Now, it's true that people are sometimes turned off by negative ads. But there is a formula that is virtually guaranteed to defuse this. You first attack your opponent, and then at the end of the ad you deny that you attacked the person and say you just want to get along and have a civil debate. Perhaps even accuse your opponent of attacking you first, and THEN announce that you "won't stoop to that level", even when you already have. People will tend to remember the last thing you told them intellectually. But they will remember the first thing they saw emotionally. Republicans use variants of this technique again and again. Fox News claims to be "fair and balanced" at the end of mercilessly displaying their bias. Many people continue to buy it.
Now I know some people might say, "but that's being dishonest". Those kind of people are really not equipped to function in an actual democracy. They are functioning in a perfect fantasy world which has never and will never exist.
So, to recap, the purpose of violent rhetoric is POWER. Whether you are defending yourself personally or your campaign politically, by refusing to meet your opponents threat with adequate stopping power, you become the victim. The key is to disguise your own responses, claiming that you are not attacking your opponent and that you have been wronged, and that you just want to be civil. However, don't drink your own Koolaid. They will come at you with everything, and you have to come at them with everything. The time for being civil is when things are over. Civility is for your friends, not your mortal enemies.