How we change what others think, feel, believe and do
Many groups use a 'higher purpose' of some kind to persuade and retain members.
The way that the 'higher purpose' is typically used is to find something that the person will accept as being of greater importance than themselves. This then may be used as a lever, framing decisions that the person has to make in terms of a choice between the higher purpose and themselves.
Depending on the preferences of the person, this 'higher purpose' may be some combination of intellectual, social and spiritual.
When intellectual value is used, the higher purpose is of rationale, of being logically right. We all have a need to explain, and showing something as being logically correct will have a particularly strong persuasive force, particularly on those people who consider themselves to intelligent and rational thinkers.
Even those of us who are not so academically gifted have a need for rightness and explanation. As long as an argument sounds reasonable (even though the logic may be shaky), then we will still tend to accept it.
Framing arguments as being a choice between putting oneself or other people first mans that taking the former choice opens a person to accusations of shameful selfishness. This is a powerful force on most of us and it is surprising what we will cede to the group.
An even higher purpose that is used for persuasion and conversion is to frame actions in terms of their spiritual value.
A person who does right may thus be saved for eternity, whilst those who do wrong may be damned for an equally long time. Spiritual reward and punishment thus tends to provide a very stark choice.
A value of spiritual persuasion is that, provided the authority that pronounces the rules is accepted as an authority, the purpose cannot be challenged. If a deity says that something must happen, then their assumed ultimate goodness and knowledge prevents any challenge.
When the higher purpose is defined and desirable, then it will attract the target person. If it is thus associated with something, then the person will be attracted to that thing.
Associate with desired actions
When the higher purpose is associated with actions, then those actions take on the significance and value of the higher purpose. To take the action is thus equated directly with achieving the higher purpose.
Such actions can range from genuine and valuable helping of others to suicide attacks that assume that personal sacrifice leads directly to promotion in the afterworld.
Associate with the group
When the group is associated with the higher purpose, then to join the group is to become one with the higher purpose. Groups thus believe themselves to be superior to others, that they will be saved when others perish, that they are more intelligent, kinder to others or more spiritual.
Again, this belief can be genuinely helpful or can be subversive and result in negative and destructive effects. People in the group, of course, do not see such actions as bad or negative. They see what they do as achieving the greater good of the higher purpose.
Thus we have racism and other forms of group bias, and nations go to war with nations, each believing that they have the higher purpose on their side.
Associate with the leader
Leaders may well associate themselves personally with the higher purpose, seeking to embody it. Sometimes this is genuine, but can also be a deliberate ploy to gain power. If you speak for the higher purpose, you effectively become it. You can thus acquire absolute power (which of course, can corrupt absolutely).
Rock-stars associate with the purpose of great music, business leaders associate with the creation of wealth and priests associate themselves with religious and mystical purposes. Each may speak with an unchallenged authority as a result of their association with an unchallengeable higher purpose.