Simon:
"Like the Mormons, JWs are a high-control group but they do not enforce these controls through violence. They have rules and want people to stick to them but it's largely voluntary."
The only reason Jehovah's Witnesses don't resort to violence is because they have no sovereign territory they can call their own. I was told that by an elder at my disfellowshipping trial "If you were in Israel you would be stoned. "I've also read the same thing in a Watchtower magazine which said that the only reason they didn't execute some of their members is because the laws of the land will not allow them.
Once these authoritarian religions gain complete control of a geographical area their laws go into effect.
By the way, some Mormons did execute their own apostates in the 19th century under a doctrine that was called blood atonement.
Another example of religions executing people were the Puritans who persecuted and executed Quakers (with whom they had doctrinal differences).