Look, I don't like it anymore than you do....but bottom line, it's a religion. Warped, weird, misogynistic...but still a religion to those who practice it.
The same mind control can be applied to many other groups (like Scientology or even the Amish if you think about it). Again, this is about the constitution and who decides what is what.
Until the Amish and Scientologists start ramming airliners into office buildings, you have the luxury being able to make that distinction.
The fact that you know with almost-certainty that neither will engage in such brutal activities invalidates your argument. It's not a fair comparison. Th Amish, after all, don't go around beheading non-conformists and infidels, and the scientologists would otherwise be in 12-step programs has they not found Tom Cruise and John Travolta.
Islam is not a religion. It never was, it never will be. It was a political tool invented by a demented camel abuser with an axe to grind. One that allowed him to create and control an army of similarly aggrieved nomads living on the edge of starvation. If the circumstances had been different, Mohammed would have simply walked into his local Post Office and went on a shooting spree, or stood for Chancellor fo Germany. Instead, he turned his attention to megalomaniac visions of world domination.