There's a lot of xenophobia.
Think of it as in/out group dynamics on steroids. You distrust those outside your group, only have bad things to say about them; you trust those inside your group, only have good things to say about them.
We do it with sports teams and geographics groups; we do it with ethnicities and races; we do it with class boundaries and education levels; we do it with political parties and even college majors. Same dynamic. As long as it's mild, it's not a problem. When it gets beyond that, you get dysfunctional systems.
Politically you get what Hanna described in Foreign Policy: "Morsi's majoritarian mindset is not anti-democratic per se, but depends upon a distinctive conception of winner-takes-all politics and the denigration of political opposition. Winning elections, by this perspective, entitles the victors to govern unchecked by the concerns of the losers." A Guardian writer paraphrased this as "ambush" style politics. All for the in-group,l and nothing for the subhuman outsiders.
Such are humans. A bit more distrust and you get the Taliban, and religion may be the form it's taking, and the concrete motivations; but the underlying theme is just one of crass tribalism and you got it just as well in the Pak tribal areas decades ago without the religious garb.