I guess the term nutjob and extremist comes to mind easily enough for me.
An observation -- "your side" (if you'll forgive the generalization") has attacked "my side" with similar vitriol. More, they've told us to LEAVE the GOP, they've said we have ought not participate in making public policy. Since none of know each other, it is our belief system that is being attacked (on both sides), hence the high emotion.