I used to attend Sunday school up until I was 17. Since I was one of the older kids, I had the job of helping the nuns teach classes full of younger kids, though they weren't usually that much younger (10 to 13 years old). One kid, who was known as the troublemaker, began insulting and hitting other students, all while the nun was talking. I waited to see if he would calm down. He didn't, so I told him to get out. The class went silent and he looked at me like I was joking, but he left anyway.
After class, one of the administrators walked up to me and asked me if I sent this kid out of the room. I said yes, and he said "Nice, but don't do that next time." Apparently there's some kind of accountability issue. That's not the worst of it, though. When Sunday school was over, this kid ran up to me and kicked me in the heel. I turned around and he stood there, swearing and laughing at me. So I palm-struck the kid in the mouth. Then he began to yell "What the f-" but I hit him again before he had time to finish. He backed off, and I got in a world of trouble with the administrator. But the kid doesn't bother anyone anymore.
See? Kids KNOW that they are able to get away with a lot of things because they KNOW people aren't "allowed" to hit them--they live in a world of entitlement. So there's no real consequence for bad behavior. All you have to do is give them real, tangible deterrents, and pretty soon, God's little angels won't be little demons anymore, the blighters.