A cult is a movement that has acquired a highly devoted but relatively small group of fans. This could be a movie, a dance, a car, or just about anything. So you can see it is… important to clearly define your term. Are you asking about a theological cult or a behavioral cult? This is an important distinction to make. A theological cult would be any teaching about God that has radically different (cultish) from the fundamental "orthodoxy" that you yourself hold to. In short, most monotheist think everyone else is in a cult, and they alone hold a corner on the truth. \n.
\nSome people hold this exclusive view (our group is right) much stronger than others, and it is this religious conviction that will sometimes lead to the "high-demand" cult behavior. This is the kind of cult that your friends and family warn you about. Here is a good definition:\n.
\nCult: A group or movement exhibiting great or excessive devotion or dedication to some person, idea, or thing, and employing unethical manipulative or coercive techniques of persuasion and control (e.g., isolation from former friends and family, debilitation, use of special methods to heighten suggestibility or subservience, powerful group pressures, information management, suspension of individuality or critical judgment, promotion of total dependency upon the group and fear of leaving it), designed to advance the group's leaders, to the actual or possible detriment of members, their families, or the community.\n.
\nFirst, cults lie to and manipulate people â their own members and outsiders â in order to further their own ends, which are rarely the same as their publicly-stated reasons for existing. A cult will almost always lie about what they believe when they think you will react negatively to the information. In a non-cult group/movement, finding out what the group believes is not difficult â you ask them and they tell you.\n.
\nA cult will frequently also lie about or avoid discussing how they are organized, who is in control, and where the money goes. Psychologically abusive groups rarely keep their members informed about the group's finances, or problems within the group, let alone making this information public. Members who leave either become non-persons or are demonized. ("Harry had a bad heart and it finally caught up with him." etc) This goes beyond any normal organization's hesitation to wash dirty laundry in public â supposedly trusted members often find out, on leaving, that they knew less about their own group than their family members and friends did.\n.
\nAlthough most outsiders clearly see that a cult members behavior is dishonest, most people in a cult don't see what they're doing as deceitful. Most abusive cults, justified to themselves lying, manipulation and breaking the law because they believe they are trying to save people from hell. In a cult the stakes are high, choices may lead to eternal damnation or eternal bliss, or so they are told.\n.
\nDR. ROBERT J. LIFTON: "Any ideology -- that is, any set of emotionally-charged convictions about men and his relationship to the natural or supernatural world -- may be carried by its adherents in a totalistic direction. But this is most likely to occur with those ideologies which are most sweeping in their content and most ambitious or messianic in their claim, whether a religious or political organization. And where totalism exists, a religion, or a political movement becomes little more than an exclusive cult."\n.
\nLIFTON, outlines eight psychological themes against which you may judge any cult-like environment: \n.
\nSOURCE: http://www.ex-cult.org/General/lifton-criteria ( Full Answer )