To see the “other” as not just wrong or different but as evil and having ill intent. Demonization is increasingly the ultimate outcome of our highly divisive politics.
Under stress, arguably all humans are capable of engaging in unconscious polarization and splitting, wherein the badness is experienced as residing entirely in the other person and the goodness all in the self. This way of experiencing the world allows people to skip the hard work of trying to wrestle with contradictions, tolerate ambivalence, and tolerate ambiguity. When we demonize someone we basically stop thinking and reduce that person to an oversimplified abstraction.