This is the Core belief for Scientologists

Most famously, all of those who reach OT level III will learn about Xenu, the galactic tyrant who stacked hundreds of billions of his frozen victims around Earth's volcanoes 75 million years ago before blowing them up with hydrogen bombs and brainwashing them with a "three-D, super colossal motion picture" for 36 days. The traumatised thetans subsequently clustered around human bodies, in effect acting as invisible spiritual parasites that can only be removed using advanced Scientology techniques. Reportedly, the cost of reaching OT III approaches $360,000[4]

Scientologists argue that mentions of Xenu by non-Scientologists are "misleading characterizations made of these writings, with altered pieces of it taken out of context putting them up to ridicule." Critics of Scientology reject this, pointing out that Xenu is part of a much wider Scientology belief in alien past lives, some of which has been public knowledge for decades. For instance, the 1958 book Have You Lived Before This Life (ISBN 0884044475) documents past lives as described by individual Scientologists during auditing sessions. These included incidents such as being "deceived into a love affair with a robot decked out as a beautiful red-haired girl", being run over by a Martian bishop driving a steamroller, being transformed into an intergalactic walrus which perished after falling out of a flying saucer and being "a very happy being who strayed to the planet Nostra 23,064,000,000 years ago".

Although definite figures are hard to come by, it is fair to say that most Scientologists are not at a sufficiently high OT level to learn about Xenu; belief in Xenu cannot be regarded as a core doctrine for the majority of Scientologists. On the other hand, as already mentioned, Scientology literature does include many references to extraterrestrial past lives and internal Scientology publications are often illustrated with pictures of spaceships and oblique references to catastrophic events that happened "75 million years ago" (i.e. the Xenu incident).

dont't believe me? http://en.wikipedia.org/wiki/Scientology

The huge thread we had that was ONE page back. (http://tinyurl.com/ce5rq)

i read the first line, and it sounded very gay, tom cruise practises that shit.