Most religious cults and negative aspects of religion are from illusions.
The common sensations people have from...
...singing in large groups
...participating in reinforcing discussions
...sharing common intimate "prayer" discussions
Produce real emotions. To oversimplify, these emotions get "translated" in the vernacular of the particular belief system.
Several totally fabricated religions use these experiences extensively. One HUGE one is the making public of private problems and the "group therapy" type vibes it gives off. This is then related to the theology of the cult.
This can be used in good ways by PROFESSIONAL therapists who are trustworthy individuals. They can manage the bonds and challenges of group therapy better. This is useful for some very sticky personal problems such as addiction, eating disorders and some character disorders.