An interesting definition to contemplate is:

The definition of a "Cult":  

1. A religion or religious sect generally considered to be extremist or false, with its followers often living in an unconventional manner under the guidance of an authoritarian, charismatic leader.
2. The followers of such a religion or sect.

A system or community of religious worship and ritual.

The formal means of expressing religious reverence; religious ceremony and ritual.

A usually nonscientific method or regimen claimed by its originator to have exclusive or exceptional power in curing a particular disease.

1. Obsessive, especially faddish, devotion to or veneration for a person, principle, or thing.
2. The object of such devotion.

An exclusive group of persons sharing an esoteric, usually artistic or intellectual interest.