Secular psychologists operate on a biopsychosocial model of human development and behavior. This model proposes humans develop and operate according to biological, psychological, and social influences. Accordingly, we are products of our biology and environment, both bearing equal importance.
In more recent years, psychologists have begun recognizing that our spirituality impacts our lives, but have yet to say it is imperative for life. While the traditional psychological theories and models that are based upon naturalism are insufficient from a Christian worldview, not all of secular psychology is wrong. Indeed, there are many helpful and positive aspects of psychology to consider, which is why there is a need for integration.
If you can change a person's belief, you have a very powerful persuasion tool. They are, however, quite deep things and will often resist changing. So understand them, how they are formed and how they change is helpful.
This is a three-stage process that is used in changing beliefs and consequently how people behave. It can be a harsh process, as used by some cults, but it is also a subtle method that even parents will use.
1. Build them up
How
Start by building their beliefs that are consistent with their current situation, affirming that they are right and good.
For self-belief, encourage them to believe they are wonderful, good, competent and so on by admiring and praising them.
For other beliefs, listen to them and tell them how you agree with them. Encourage and exaggerate these beliefs.
Why
As you show that you believe in them and their beliefs, they will trust you more, bonding with you and and connecting their beliefs to yours.
This sets you up as an authority on what is good and bad, right and wrong. In framing you as a reference person, they make your evaluations even more true and hence intensify their own beliefs.
Example
Parents do this when they tell their children they are wonderful or have great potential.
Sales people do this when they ask customers what they like and empathize with their priorities.
Cults do this through such as the love bomb, where they keep telling the target person how wonderful they are and that they believe in their inner strength.
2. Knock them down
How
Find ways in which the belief is wrong or bad, breaking values or acting against needs.
Then pull the rug from beneath them, telling them they are disappointingly wrong or bad. Frame wrong acts they have committed as being far worse than their better attributes, making them in sum a bad person.
In a more gentle way, you can simply disapprove or otherwise show you are less than happy with them.
Why
When you have become an authority, this gives you the position to be judge and jury. Having accepted your praise, they must now accept your criticism.
When your identities are joined, a threat to pull away from them feels to them like they are being pulled in two.
Example
Parents do this when they find their children misbehaving or not doing well enough at school, and tell the child how disappointed they are.
Sales people do this when they point out problems with the customer's desires and contradict related beliefs.
Cults do this by using the confusion of identity destruction, where they break the person's self-belief, reducing them to an emotional wreck.
3. Rebuild them
How
Show you are still on their side but hint that you will abandon them if they do not change their beliefs and mend their ways.
Show them the way to regain your admiration, by believing what you say is right. Indicate the right things for them to believe and do. Support them in their transition to the new way.
Why
When they feel ashamed and broken, and perhaps that you have abandoned them, they will grasp gratefully at the straws you offer.
This not only gives them a way out, it also reinforces their view of you as a considerate and powerful person.
Example
After scolding a child, parents offer a way out by gently telling the child what is right and reaffirming their belief in the child's basic goodness and potential.
Following careful criticism of their initial choices, sales people show customers the best options, explaining why and so developing new beliefs in good and bad products.
After identity destruction, cults rebuild the person as a blindly-believing cult follower.
So what?
Use this carefully. It can be done gently and it can be used in a very harsh way. Harsh methods often have a backlash and should be avoided if at all possible.
As a three-stage process it can be very much focused on belief change. It can also be less about belief and more about how people behave, although belief change may still happen along the way.