Of course they exist, as do Christian extremists, Hindu extremists, and there are probably psychos waiting in the wings who are afiliated to the Flying Spaghetti Monster. However I think the Orlando nutter was just that, a nutter, who also happened to be of Islamic extraction. He was such a devout adherent to IS' philosophy that he, apparently, frequented this particular gay bar, met men on gay dating sites, and was often drunk.