They are closed-minded. They have nothing to say of themselves so they look down at other people and see what they're about or what they think they know. People are just people. It doesn't matter...
We can see in the legal codes of the Middle Ages that some people believed in, and feared, witches. Such belief is not easily derived from Christianity, which has only rather ambiguous scripture...
Every one has a reason for thinking the way they think.
maybe something that has happened in their past or that happened to them recently also depends how a person is: are they quick to judge, do...