http://en.wikipedia.org/wiki/Cult#Origins_in_sociology
The word cult pejoratively refers to a group whose beliefs or practices are considered abnormal or bizarre.
This is strictly in the mind of the beholder. It has been said that Hinduism is a religion of 330 million Hindu gods. That in itself is bizarre in my mind. Jehovah's Witnesses teach what only makes practical sense: that Adamic sin won't persist indefinitely while an immortal soul floats off to heaven or hell at death. That God has some purpose and hasn’t abandoned the planet he created.
The word cult originally denoted a system of ritual practices. The narrower, derogatory sense of the word is a product of the 20th century, especially since the 1980s, and is considered subjective. It is also a result of the anti-cult movement which uses the word in reference to groups seen as authoritarian, exploitative and that are believed to use dangerous rituals or mind control. The word implies a group which is a minority in a given society.
"Mind control" is nothing short of science fiction.
http://en.wikipedia.org/wiki/Cult#Mind_control
In the late 1980s, psychologists and sociologists started to abandon theories like brainwashing and mind-control. While scholars may believe that various less dramatic coercive psychological mechanisms could influence group members, they came to see conversion to new religious movements principally as an act of a rational choice.
Steven Hassan (Mental health counselor, advocate of exit counseling, author of two books on the subject of "cults") simply made a personal decision based on his own outlook on metaphysics and reality that worked for him. He doesn't necessarily subscribe to the facts of modern psychology.
To anyone stuck on the fictitious thinking of Steven Hassan and like minded: The only real "mind control" that can be spoken of was instituted during the Dark Ages as no one could teach anything outside what was official church doctrine without being subject to capital punishment.
There's quite a bit of ambiguity and uncertainty when defining a cult.