“Perpetuate” the Crusades? I presume now that a Muslim Europe would have been fine from an historical perspective now? So much for alleged historical accuracy.
The Crusades were not, mostly, fought in the defense of Europe.
What we normally think of as “The Crusades” were fought to recapture parts of the Middle East. They were a failed counterattack, not a defense.
There were, of course, “crusades” in Iberia, the Balkans and elsewhere that were in defense of Europe.
BTW, many “crusades” had nothing at all to do with Islam. The Popes launched them against Hussites, pagan Prussians, and even the Holy Roman Emperor and their domestic Italian enemies.