There is a group which doesn't get mentioned much on websites or in cult books. It started in Vienna in the late 1970s and early 1980s. Its founder was a man named Gottfried Holic (he has since died). It is known by various names. Sometimes it is called the Dunafoldvar Christians, and sometimes it is called the Holic Group. A Hungarian sociologist, Istvan Kamaras, has written at least two articles about it. In addition to Vienna, it has several cell groups in other Central European countries.
The does not have a name for itself. When asked, the members simply identify themselves as Christians. The other names for it have been given to it by those who study it from the outside.
Its cell groups are small, perhaps twelve to fifteen people per cell. There is usually one cell per city. On most weekends, several cell groups will meet together as a larger group. The group is secretive, and so the number of members is not clear, nor is the number and location of the cell groups.
It targets younger people, roughly aged 17 to 29, who are Christians. The group presents itself as a home-based church which lives according to the teachings of the New Testament and follows the patterns and lifestyles of the earliest church.
Once a young person has fallen under the group's thought control, however, the first step is to isolate the individual by breaking off all contact with friends and family. This group is extreme in this regard: it achieves a greater degree of isolation than many other cults. Its members can go months and even years without contact friends, family, or even parents.
Some information about the group is found here:
I hope to share more about the group in this form soon.