Well, it's not that outlandish. Mind control, brainwashing, thought reform, manipulation, coercion, mind-hacking, call it what you will - the methods have been used in prison camps, totalitarian regimes, religious and political groups, everyday relationships, and even work environments. And despite popular believe, anybody can fall prey to them. It's not about being smart enough, it's about being educated on the specifics, and then noticing the warning signs.
The techniques of brainwashing are quite simple (bpdcentral.com):
isolate the victim
expose him/her to inconsistent messages,
mix with sleep deprivation,
add some form of abuse,
get the person to doubt what they know and feel,
keep the person on his toes,
wear him/her down,
and stir well.
At a very basic level, brainwashing makes a person question their beliefs or reality. Without any pressure, a person slowly evaluates the new information and either discredits it or incorporates it in his belief system, based on current evidence and past experiences.
However, with the addition of components of fear, such as physical intimidation or spiritual threats (i.e. "the world is going to end"), and isolation from others who could provide critical input, then the victim is likely to subdue to the influence of a skillful manipulator.
Dr. Robert J. Lifton's Eight Criteria for Thought Reform
Milieu Control: This involves the control of information and communication both within the environment and, ultimately, within the individual, resulting in a significant degree of isolation from society at large.
Mystical Manipulation: There is manipulation of experiences that appear spontaneous but in fact were planned and orchestrated by the group or its leaders in order to demonstrate divine authority or spiritual advancement or some special gift or talent that will then allow the leader to reinterpret events, scripture, and experiences as he or she wishes.
Demand for Purity: The world is viewed as black and white and the members are constantly exhorted to conform to the ideology of the group and strive for perfection. The induction of guilt and/or shame is a powerful control device used here.
Confession: Sins, as defined by the group, are to be confessed either to a personal monitor or publicly to the group. There is no confidentiality; members' "sins," "attitudes," and "faults" are discussed and exploited by the leaders.
Sacred Science: The group's doctrine or ideology is considered to be the ultimate Truth, beyond all questioning or dispute. Truth is not to be found outside the group. The leader, as the spokesperson for God or for all humanity, is likewise above criticism.
Loading the Language: The group interprets or uses words and phrases in new ways so that often the outside world does not understand. This jargon consists of thought-terminating clichés, which serve to alter members' thought processes to conform to the group's way of thinking.
Doctrine over person: Member's personal experiences are subordinated to the sacred science and any contrary experiences must be denied or reinterpreted to fit the ideology of the group.
Dispensing of existence: The group has the prerogative to decide who has the right to exist and who does not. This is usually not literal but means that those in the outside world are not saved, unenlightened, unconscious and they must be converted to the group's ideology. If they do not join the group or are critical of the group, then they must be rejected by the members. Thus, the outside world loses all credibility. In conjunction, should any member leave the group, he or she must be rejected also. (Lifton, 1989)