If you want to understand the moral sickness at the heart of leftism, read the first paragraph of the most recent column by Washington Post columnist E. J. Dionne:

It’s never right to call other human beings ‘animals.’ It’s not something we should even have to debate. No matter how debased the behavior of a given individual or group, no matter how much legitimate anger that genuinely evil actions might inspire, dehumanizing others always leads us down a dangerous path.