There are people who are fanatically devoted to their religious leaders. I believe it is a voluntary slavery, and I think that these people are dangerous to society. It is from these people make terrorists. How can you raise a hand to their children?
There are religious sects such as Aum Shinrikyo and Jehovah's Witnesses, who try to enslave the ordinary follower by means of blackmail and threat. This slavery can take many forms, and it can be of economic or sexual nature.
Yes, now there are so many sects that destroy humanity. From such a sect it is very difficult to get out if they drag it.
Aum Shinrikyo is just a plain old terrorist group. JW tend to be well-behaved, at least here in my country. I guess what really makes the cut when it comes into intimidation is Scientology. They'll definitely give Jim Jones a run for his money.
This is the problem with most religious groups, they tend to spawn sects and unfortunately not all of those can be called moderate. Even with people drinking the holy kool-aid every now and then, it seems we haven't learned enough. Government could be helpful with this, but then again they tend to stay away from religious issues unless it has already become a huge problem or it has already caused a media scandal.
Why harm a person just because God wanted it. 
