Here is an a short article I liked a lot. It explains the dynamics we often see in our former groups.
Why Bad Beliefs Don't Die
Gregory W Lester asked "Why Bad Beliefs Dont Die" (November December 2000). Some other answers are admirably explored in Expecting Armageddon: Essential Readings in Failed Prophecy, edited by Jon R. Stone (Routledge: New York and London, 2000). First of all, bad beliefs are usually part of a complex ideological system; for example, when Jesus Christ did not usher in the Last Judgment on April 23, 1843, as preacher William Miller had predicted, his followers drew on many other shared beliefs and experiences (for instance, the importance of avoiding sin and the catharsis of banding together in prayer groups) to comfort themselves amidst the failure of Miller?s prophecy. Thus, instead of being deprived of a core belief, the adherents usually feel they have simply lost one of many equally important beliefs. And while one prediction may fail, others will be fulfilled by random chance alone, so long as the prophetic leader is shrewd enough to make multiple (and flexible) forecasts of future events.
Secondly, when beliefs are disconfirmed, their adherents simply revise them spontaneously and retroactively; for example, if the world did not end physically on a certain day, then it must have ended spiritually, and we the believers are now the enlightened citizens of the world beyond. (Or, perhaps, we did not ?deserve? to have the prophecy fulfilled; thus, the prediction was rendered false by our own failure, not that of the prophet.)
Finally, beliefs survive best when their adherents feel they are part of a cohesive community; an ideologue who gives his followers a sense of ?belonging? has already won the battle against skeptics who seek to disconfirm his teachings. His followers can simply point to all the other members who still endorse the beliefs, prophecies, or principles that have not (yet) been disproven. The more of these people there are, the greater the ?proof? that the leader speaks the truth. ?How could so many of us all be wrong?? the believer will ask.
Skeptics who criticize illogical group beliefs need to be aware of these realities. ... More importantly, skeptics need to remember that the people who buy into such beliefs are seeking a sense of meaning in their lives. The reason they so viciously resist the assault of logic is because they cannot bear to be stripped of their sense of belonging. Their devotion to the charismatic founder of their group makes them feel both protected and privileged, often for the first time in their lives. . .
New York, NY
SKEPTICAL INQUIRER March/April 2001 page 65