I think the point he's trying to make is that Islam is the only religion where the part about going out and killing the infidel isn't made up by some extremist faction, but is codified in the religion itself.
You could argue that the Jews were instructed to do so as well, but they were only commanded by god to inflict genocide on very specific groups of infidels, not the entire infidel population. But score! God let the Jews rape the plundered bitches just like the Muslims!
I'm aware of the parts of the Gospel where Jesus says he's here to make the world go crazy, but I'm not familiar with the parts where he instructs his Apostles to go out and slaughter everyone who doesn't convert. I believe that therein may lie the point he's trying to drive home.
You know, it's the little things like when your religion actually TELLS you to go killing everyone that set it apart from silly little sects like the Branch Davidians , Westboro Baptist Church, etc. And then there's that whole thing where Muslims like to kill everybody, all the time. It's a little more concerning than some silly signs about fags.