I am not surprised.
They're not a "large religious organisation", they're a cult.
They have the same patriarchal structures that the Catholic Church has, that enable sexual abuse, and on top of that, their members aren't allowed to socialize with outsiders, which means they can keep things quiet even better than a regular Church.
YANBU to be appalled, but I am not surprised anymore.
Shocked that they were registered as charity, though. 
No idea how they managed that.