Do you respect Jews?

For the sake of argument I shall take your lack of understanding literally - not to justify such practices, but to make it more mundane and less intimidating.

As I was taught, I can only explain the practice of hating on a certain group of people by the notion of a so-called 'mental shortcut'. Apparently, people prefer to see the world through a certain framework which helps them to "understand" (or make sense of) it better. In a way, we all make use of mental shortcuts; the difference lies in what we decide is relevant to us (or to be precise: our survival).

For some people, to see the nuance between individuals in posession of a certain trait that they have in common (for example, the religion that they practice or the ethnic background that they have) is too much work - this is where the factor of intellect plays a big part - so they fall back on the clustering of the information that they either acquire or are bombarded with (by the media, for example). I suppose the best way to counter such rigid and simplistic ways of thinking is through challenging their prejudice.

Case in point: you may want to check whether Muslims truly "share" their religion with IS, for instance. Rather it is IS that under the guise of religion kidnaps and tortures Muslims and enforces their own rules on them. I think it has little to do with faith, and everything to do with power (and possibly money).