The shelf life of sin is interesting, but the real damaging element for many of us was the fear of thought sin. The book publishing business hammered that over and over. To think sin was to sin . . . . and don't trust your own mind because you might have an independent thought and question the unquestionable.
Once members are taught to not trust or to fear their own thoughts, they give up critical thinking, or if they have a rational thought they recognize it as weakness and re-set themselves back into the group mindset by chanting, or repetitious verse reading, or ritual meeting attendance, or unpaid religious literature distribution.
The Way I See it http://www.freeminds.org/buss/buss.htm