It's more of a political issue than religious. When it comes to Islam though, people often speak of these as one. Our media is mostly to blame for this.
As for the general hostility from the Islamic republics, I would think it's only natural for a republic to demonstrate such behavior when they have been oppressed for decades.
Just to make sure, I speak of modern times. By modern times, I mean the last few decades. I hope that was elementary enough for all of you.