The 'cult' word is inflammatory. Waco, Heaven's Gate, Jim Jones come to mind...weird extreme fanaticism, mass suicides. To some, Mormonism is a blatant cult; to others its just a different version of Christanity.
We'd like to be clear how we use 'cult' and 'cultic' on this website. We are not implying that a group is weird and fanatical and the kool-aid is on the way. Nor are we using it in the sense the Christian community often does, to mean that a group holds outspoken unorthodox doctrine.1 Many cultic Bible-based groups appear to hold quite orthodox doctrine, and are accepted by the wider Christian community as one of themselves.
Rather, we use the term in the sociological sense,2 to refer to groups that have a specific set of characteristics: they are authoritarian, legalistic, punitive, and exclusive. Usually there is a heavy emphasis on performance. Prospective members are not completely informed about the group's agenda before they join. Once they have become part of the group, they are informed that they can't leave without incurring dire spiritual consequences. On this site we are particularly concerned with Bible-based groups that function in this manner.
For a fuller discussion of this concept, see Definition of an Abusive Group
2 "Sociological definitions of the term...include consideration of such factors as authoritarian leadership patterns, loyalty and commitment mechanisms, lifestyle characteristics, [and] conformity patterns (including the use of various sanctions in connection with those members who deviate)." Ronald Enroth, ed., A Guide to Cults and New Religions, Downers Grove, Il., InterVarsity Press, 1983, p. 14.