I always avoid the crusades when I am time traveling.
Actually, the Crusades were a response to the first Jihad....at least at first.
Could you please take me back to 5pm this afternoon before my car got totaled by a hit and run driver?
Still, most people imagine the events in Spain as being the actual Crusade ~ there they had back and forth warfare for several hundred years ~ but it wasn't unrestricted. The Jews got to be Jews, and the peasantry would be forced to adopt the religion of their prince of the moment ~ whether Moslem or Christian.
Nobles were kind of independent of that and just moved around to whatever principality would pay them the best.
French knights regularly earned their spurs in Spain.
Spain actually developed relatively permanent laws regarding "forced conversions" ~ and one of the last requests by the last Moslem prince was that there be no forced conversions.
His request was, of course, rejected!
Alas, Spain didn't have a crusade, it had the Reconquista. It was interrupted a couple of times by yet more Middle Eastern/North African invaders who sought to enforce a stricter orthodoxy (Sharia law) on the Moslem princes, and that wasn't all that popular with Jews, Christians or Moslems.
What about the ones in the future? Are those avoidable?