Now would be a good time to look into social psychology. There indeed exist normal groups that are "religions," but simultaneously, cults exist as well. These use many psychological methods to ensnare unwary ones by changing their thoughts, perceptions, and feelings.
Cults do exist and can be dangerous. They can change a person's entire way of thinking and make them believe that their cult is the only way to salvation. They may propagandize extensively and inculcate individuals with seemingly valid thoughts that contain gaping holes.
CSJ.org is a site that studies cults. See if your friend's group is listed. Many of these groups share similar techniques such as skewing logic and separating all people into two groups (one will get saved, one will get destroyed) etc. Very dangerous. Basically, read up on mind control and cults; they exist and they're powerful.
A group of veterans in Vietnam were brainwashed by people there. They were given small requests such as giving out their name, rank, and serial # at first. Gradually, they were asked to make videos showing that they were safe or showing that POWs were not mistreated. Eventually, step by step, they were willing to go to extremes, and they were tought that communism was right. Many veterans even stayed in Vietnam or other Asian areas after the war and refused to return to their homelands. That's brainwashing.
<--has been in a "cult" before and has since left after debunking its logic system.