As your article mentions, they tell members to ignore outsiders, including friends and family. The Bible-study leader would then pick out appropriate passages for that recruit, but act as if they were random, or straight from God. In this way, it would seem to the recruit that God was speaking directly to him. It seems that cults are on the rise. This is something that will become especially widespread as we approach the year 2000, which holds a magical significance for many cults.
Education is the best weapon against cults.
There will always be somebody who is so vulnerable that they may be taken advantage of by a cult. However, by teaching the potential harms of cults we may be able to reduce the number of people who fall prey.