This danger is much like the danger from radicalized Muslims in that it's really more a symptom than a root problem. The root problem is Leftism. Cultural Marxism, Critical Theory, whatever you want to call it. These problems are like opportunistic pathogens taking advantage of a host that has been weakened by some deeper infection. Were it not for that deeper infection, the host's immune system could almost casually swat away the opportunistic pathogens.
The real cause of this is the smarmy liberal from down the street, with the Subaru and/or Prius and the "Coexist" bumper sticker. They're the ones deliberately driving over the fire hose so that the water can never reach the flames.