How Cults Work From the site, How Cults Work, we have this explanation of what is known as Exclusivism, something found in many religious cults:

"A normal religious organization would not have any trouble with you moving to another similar organization as long as you stayed in that same religion. Because it is the belief system that matters, not membership in an organization. For example if you were a Christian then you could move from one church to another and still be a Christian."

"However cult leaders will tell you can only be "saved" (or can only be successful) in their organization alone. No other organization has the truth, all others miss the mark. So it is not the belief system that decides your future, but it the belief system AND your membership with that particular group."