People across the spectrum are horrified by the shooting, especially progressives. Among my progressive and liberal friends, they were all dumbfounded by the fact that a liberal, Bernie supporter could do such a horrific act. This man assisted with the Bernie Sanders campaign, and he had a sign that said "tax the rich like congress did for 70 years till Reagan's "Trickle Down". So how could a man that believes in the ideals of modern liberalism, equity, fairness, and social justice do such an act? Isn't this an act that is usually attributed far-right religious fanatics?
I'm trying to make a strange parallel, so bear with me. After Nietzsche said "God is dead" in his book "The Gay Science" in Germany in the 19th century, it was not statement of affirmation. It was a statement of trepidation. He thought that if Christianity died then the foundations of which Western Civilization will fall as well. He wrote in Twilight of the Idols "When one gives up the Christian faith, one pulls the right to Christian morality out from under one's feet. This morality is by no means self-evident... Christianity is a system, a whole view of things thought out together. By breaking one main concept out of it, the faith in God, one breaks the whole." The rejection of universal moral beliefs would lead people to nihilism or at least lead people adopting pseudo- religious ideologies. Nietzsche was correct; after Christianity has lost its influence on the West, nationalism and communism took root to replace Christianity's order. But once those ideologies fell, the western liberals decided to substitute those with ostensibly more friendly ideologies like feminism, progressivism, and veganism. The problem is that any ideology can turn pernicious, no matter how strong you claim the bedrocks of your dogma lies on.
Because the left wing side of the west is more secularized than the right, you won't see fanaticism towards a radical, hostile perspective of Christianity. You will see radicalization of secular- religions like social justice and progressivism. These campus riots and republican attacks are all examples of progressives becoming radicalized.
Bernie Sanders did well to condemn the violence that was enacted. But do not think this will be the last time a person claims progressivism for violent intent. Unless the left can do a better job to self-regulate themselves, then these acts will continue.