Core teachings alone doesn't keep people enslaved.
You have to eradicate their true personality by:
Destroying their ability to think for themselves.
Undermine their self esteem by constantly reminding them of their sinful inclinations.
Then "lovingly" provide the antidote to their woefull condition -in this case obedience to the GB.
Genius marketing strategy really, create a fictitious need, then provide the exclusive cure.