Cults fail due to bad marketing practices.
To say that your group has the ONLY truth, the ONLY way, and all others are satanic, or stupid, or invalid...that's bad marketing. No product would sell if presented that way. "This car is the only vehicle that can provide transportation"? "This restaurant has the only good food in the whole world"? See how silly that sounds.
Why should belief systems be any different from any other product?
Cults self-destruct via many avenues. Arrogance blinds the leaders. Since they permit no criticism, they receive no helpful feedback, and they do whatever they want, which eventually backfires.
Recent example: if a cult lets the media film their compound, and there are no toys, no books, no TV or radio, but lots of photos of the cult leader everywhere, that's a huge mistake. That little tour of the cult's facilities just proves that mind control is happening there.
Mind control is excessive influence of one person over another, for the controller's benefit (thought it's usually presented as "helping" the chump). Dominating another person is a sadistic act to begin with, and all subsequent cruelties stem from that original impulse to subjugate someone else. Controlling personalities are everywhere: in families, offices, clubs, romantic relationships, schools.
Bullies take great pleasure in hurting and humiliating others. They are misanthropic: haters of other human beings. Cult leaders, tyrannical husbands, dictators of nations, malicious police officers, slave-driving bosses, and egotistical friends who criticize you, but accept no criticism of themselves -- these personalities are all cut from the same cloth.
It's "command and control": the opposite of debate, exploration, discovery.
This is why the internet, particularly forums and the blogosphere, represents a serious threat to cults, totalitarian regimes, and con artists. People now can investigate, not only companies and products, but also persons and groups, and discover what others have to say them.
Comments that have the most credibility are the ones that seem balanced, rational, not overly emotional, not bitter or hateful, objective, with no ax to grind, specific, and a bit inarticulate. Why "inarticulate"? Because a spontaneous remark, dashed off in a hurry, by a sincere person is often awkwardly worded, whereas a carefully devised statement tends to sound more like PR, advertising, or cult indoctrination.
You teach your children survival skills, right? You teach them how to talk and walk and be polite. You must also teach them how to protect their mind.
Protect their mind! If you capture a person's mind, and dominate all their thoughts, that person no longer has a soul, no longer has a distinct individual existence. Once a person is totally dependent on a group or leader, and will not question them, that person is in a very vulnerable spot. Who knows what they'll be forced to do next?
Blind obedience can result in genocides, group suicides, and other tragedies.
Children must be taught, by their parents, how to detect and resist cults.
Thinking independently begins with being curious. Who wants to be a mere parrot, just repeating what everybody else says? You take something that is said by your mom, dad, pastor, priest, teacher, best friend...and you ask "Is that really so? Could there be more to it? What does the opposition say?"
To surround yourself with people who agree with you is the mark of an insecure person, which is what domineering persons are. "You must hate what I hate, or I'll hate you," is the unspoken, hidden engine driving those who wish to dominate others. "You must love what I love, or at least never speak ill of it. If you don't mirror me, I shall destroy you."
Curiosity is the key. You eventually get sick of having all your opinions and beliefs shoveled into your mind like sludge. You wonder: "Is this really the ONLY valid viewpoint?" You get interested in learning how an opposing view is presented, what it's based on, and if there might be a little kernel of truth in it, something you can learn.
I read once that a form of Buddhist training is to teach young monks every other philosophy and religion first, prior to teaching them any Buddhist ideas. The students are taught, in a non-hostile manner, what other belief systems teach, so they can discuss issues with non-Buddhists in a friendly and educated manner.
Practically every belief system has elements that are either true, or valid, or are counteracting some excess in another belief system.
One can be against war, but sympathize with those who join the Army from a desire to defend and protect their country. That is a noble impulse and should be encouraged. But to think that all wars are "just", all military commands must be obeyed even if they violate the Geneva Convention, and military action is the only or the best solution, this is very lopsided and narrow-minded thinking.
If you can't question a human leader or institution, that entity is authoritarian, totalitarian, and misanthropic.
One of the best things you can do for a child is teach him or her how to be "different", how to question their peers and leaders, how to despise popularity as a way of reinforcing a flimsy self-esteem.
You can find a lot of good information on cults, brainwashing, and indoctrination on the internet.
The Cult Test provides 100 aspects of a cult, with explanations and examples. Here's a sample. It's a bit long of a quote, but the material is well presented and reasoned.
1. The guru is always right.
In cult after cult, the leader is just the greatest thing.
"Ultimately you cannot admire the guru, you must worship him."
If you have any doubts about whether the cult worships the guru, just ask a member, "What are the 10 biggest mistakes that the guru made in setting up the organization and formulating its doctrines?" True believers will give you a look of horror and insist that the guru has never made any mistakes... "The very idea is unthinkable."
There is one big disadvantage for the guru when the cult declares that he is perfect -- he has to act that way, and at least do a good job of faking it.
If he is found to be stealing all of the money and screwing all of the girls, it can hurt his believability. A few cults have a clever work-around that spares the cult leader from having to be perfect: Somebody Else, like a dead saint, or an angel, or Jesus, or the Virgin Mary, is the perfect one, and the cult leader merely "channels" the Perfect Master's messages.
In that way, what the leader says is still unquestionably true and unchallengeable, because it comes from a Higher Power, but the cult leader can indulge in all of the pleasures of the flesh himself without creating a contradiction.
After all, he never said that he was perfect, or any more holy than anybody else. He is just more attuned to the Higher Spheres, and able to hear the Voice of a Higher Power... Oh, and of course the received messages will suit the leader's whims.
Suppose, for instance, that there is a cute young woman whom the leader fancies, but she has gotten involved with another male member of the group. Well, suddenly the Angel or Ascended Master is criticizing that other fellow for indulging in base desires, and telling him to knock it off and have nothing to do with women.
Then, when the cult leader jumps on the same young woman, the Ascended Master has no criticism of him... Funny how that works. You can use your own imagination to dream up another dozen similar tricks.
2. You are always wrong.
The individual members of the cult are told that they are inherently small, weak, stupid, ignorant, and sinful. Cult members are routinely criticized, shamed, ridiculed, discounted, diminished, and told in dozens of ways that they are not good enough.
This cult characteristic is sometimes expressed in the infantization of the cult members: They refer to the leader as "Father", while he refers to them as "my children."
Cult members are also told that they are in no way qualified to judge the Guru or his church. Should you disagree with the leader or his cult about anything, see Cult Rule Number One. Having negative emotions about the cult or its leader is a "defect" that needs to be fixed.
A corollary to this rule is the practice of lowering members' self-esteem by a variety of methods: Elders or higher-ranking members will berate the newer members and tell them that their work or their spirituality isn't good enough. Again, the beginners are abused by the guru and his henchmen until they reach the inner circle, at which time they can turn around and do it all to someone else who is just beginning.
It is almost a universal cult characteristic that, in the opinion of the cult leader and other elders, newcomers cannot think correctly. They are too "new", or "unspiritual", and they haven't been members long enough, or they haven't prayed or chanted or meditated long enough, or they haven't been off of drugs and alcohol long enough, or something... It's always something.
Members will criticize themselves and confess all of their sins and faults, sometimes engaging in public self-criticism or confession sessions. This is used by everybody from Maoist Chinese Communist groups to Christian cults. Sometimes other members will attack them and criticize them in "group therapy" sessions, or Synanon games.
Members are taught not to trust their own minds or their own judgement:
Your thinking has been corrupted by sin.
Your judgement is no good.
Your thinking is no good.
Your mind is no good.
You have a criminal mind.
You have an alcoholic mind.
You need a complete make-over.
Your thinking is controlled by your addictions.
Your thinking is controlled by your sexual desires.
Your thinking is controlled by Satan.
You haven't been chanting or meditating or doing yoga long enough to have a clear head.
You haven't been off of drugs and alcohol long enough to have a clear head.
Members are taught not to trust their own motives: Your motives are no good; everything you do is just for yourself. You are selfish, vain, egotistical, self-seeking, and always trying to get your own way. You are just seeking ego-gratification. You are lazy. You are always trying to do things the easier, softer way. You just want to get laid. You just want to get drunk or high. You just want to avoid the hard work of getting right with God. You just want to be happy.
Members are taught not to feel their own feelings.
Steven Hassan wrote
Since mind control depends on creating a new identity within the individual, cult doctrine always requires that a person distrust his own self.
Combatting Cult Mind Control, Steven Hassan, 1988, page 79.