Whether it is in politics or revolution or just some -ism, there are and have always been the true believers. These are the zealots who enforce adherence to the message. The fanatics willing to punish any and all who fail to conform to the dictums of their pet cause. When relegated to the level of foot soldier they are the perfect cannon fodder. Over zealous in their pursuit of their objective. When they are the leaders of a group they are capable of creating hell on earth. Willing to sacrifice all scruples, any morality, and multitudinous hordes to their cause.
An essential component of the true believer is a sublimation of the rational for the emotional. When confronted with facts contrary to their point of view, the true believer will become more set in his or her point of view. They will be even less open to new or contrary ideas. The offending party who points out the inconsistencies or provides the contrary facts must be silenced. His or her position must be discredited. Fear of the person and their position must be generated in the larger group so that the group is not tempted to turn from the true message.
Control of the true believer by their leaders is easy. Convince them that those who are not ideologically pure or pure in message are actually out to destroy them and their way of life. Convince them that if the movement fails, they will be enslaved, imprisoned, or that everything they hold dear will snuffed out. Encode in the true believer that all that is moral and pure and right is contained within the movement, all that is evil, immoral, and polluted is represented by their opponents and would be oppressors.
Keeping the true believer in a heightened emotional state of fear, paranoia, anger, and hatred is no easy thing. It takes a lot of energy to maintain this state. The key is to keep them at a base level of these emotions and then spike it at regular intervals. This can work well if there is a big target, or several big targets, that are opposed to the implementation of the groups agenda. Selective soundbites and twisting of words has always worked well.
Beware the true believer for they are always searching, always trying to root out those whose purity is insufficient. Beware the true believer for like an abused dog, he or she can turn on their masters or their fellow dogs in an instant. Beware the true believer for they are far better at destruction and revolution than they will ever be at building a stable society.