Is Scientology a "cult"???
Yes, in my opinion it is. Now first of all, let's define what I mean by "Cult" .
To my mind, a 'cult' is a group, either religious or secular, which behaves in an authoritarian manner, seeking to completely govern the lives of it's followers. Many times these groups practice one or more forms of Mind Control.
"Ooooh! `Mind Control` you say?"
Yes… Mind Control. Brainwashing. Undue and pervading influence of one's behavior.
Not all 'cults' are religious in nature, nor are all cults destructive. For example, I consider some groups within Amway to be cultic.
Steve Hassan's page has a good definition of cults vs. destructive cults.