Actually, there is a difference. The Crusaders had the blessing of the Pope, whereas IS would be pretty hard pressed to find any support among Muslim nations and clerics, especially in the wake of their gruesome killing of a Jordanian pilot. Even IS recognizes this as a serious PR blunder, as it appears to have united the Arab world against them.
It wasn't that long ago that you would see Blacks lynched and even burned alive in the South by the KKK for having the audacity to stand up for their civil rights. Yet, it was decades before an anti-lynching bill was ratified by Congress and the White House. This homegrown "religious order" firmly believed it was carrying out its actions in the name of Christianity and spread throughout the South and Midwest. Here again, religious conservatives don't want to be reminded of their past.
Neoconservatives like David Brooks think otherwise, showing admiration for Obama's speech and believing the whole outcry against the President's comments "falsely manufactured."
Indeed, it seems most stories are falsely manufactured these days, largely to agitate the viewing audience much like those "Muslim" rogues in WWE "wrestling" that fans loved to hate. They've been around for quite a while, but the latest incarnation Muhammad Hassan seemed to have a little more complexity than past Muslim "bad guys," although his promising career came to an abrupt end with a graphic staged depiction of radical violence on the same night as the terrorist bombings in London in 2005.
This isn't much different than the way the news media stokes fear of a radical Muslim takeover, not just of the Middle East but of Europe and the United States as well. We are fed violent images meant to anger us and inflame our emotions. It also helps serve IS, which wants widespread circulation of its executions, essentially turning its assault into an all too real "reality show."
It's a good thing they didn't have television back in the 14th century. However, the marauding "horde" did the next best thing -- leaving the butchered bodies strewn on the ground, or piled in heaps to remind others of the fate that awaited them if they crossed the wrong path.
There appears to be an utter lack of perspective in mainstream media today and this is a very worrisome thing. The general audience feeds on images rather than on an understanding of events. Pundits use these events as whipping posts to foment their contempt for political rivals and existential threats, much the same WWE wrestlers get into shouting matches before they take to the ring.
Here we are seven centuries removed from the first Mongol invasion and the Crusades and we still think pretty much along the same lines. Sadly, the media is all too willing to reinforce these grotesque stereotypes.