A 'South Park' episode from 2005 perfectly explains Scientology's unbelievable theory of how the world began

Now that Alex Gibney's new investigative documentary on Scientology, "Going Clear: Scientology and the Prison of Belief" is in limited release, everybody is talking about its bombshell revelations about the church.

One of the biggest is Scientologists' answer to how the universe began and the secret of life. The incredible story that Scientologists believe involves a galactic overlord by the name of Xenu, a volcano, and souls that attach themselves to newborn babies.

The story may sound familiar, either for those who have studied Scientology or viewers of "South Park."

Back in 2005, the creators of the Comedy Central show told the same story in their famous episode, "Trapped in the Closet."

The episode follows character Stan, who, after taking a free test from the church, learns his results are so high that the leaders of the church have declared he's the reincarnation of Scientology founder L. Ron Hubbard.

Scientologists, including John Travolta and Tom Cruise, visit Stan's house to pay their respects. But Cruise goes to hide in the closet after Stan tells him he's not a good actor.

This then leads to a parody of R. Kelly's rap opera, "Trapped in the Closet," as celebrities ranging from Nicole Kidman to Kelly try to talk Cruise out of the closet. While this takes place, Scientology's president shows up to tell Stan what Scientologists believe in.

Many parts of the episode include the text "This is what Scientologists actually believe" at the bottom of the screen during the retelling, because to many it sounds so unbelievable, or like a parody.  

Here's what Scientologists believe.

75 million years ago, there was a galactic federation of planets ruled by Lord Xenu. 

Xenu thought his planets were overpopulated, so he gathered aliens from all different planets ...

... and had them frozen.

Those frozen bodies were packed into galactic cruisers, which looked like jet-liners, except with rocket engines, and were brought to Earth.

The frozen bodies were dumped into the volcanoes of Hawaii.

The aliens died, but their souls floated to the sky.

Xenu had prepared for this.

He didn't want their souls to make their way back to the federation of plants, so he had the souls gathered by giant soul catchers.

The souls were taken to a brain washing facility Xenu built on Earth.

They spent days being brainwashed, which tricked them into believing a false reality.

Those souls were then released and roamed the Earth confused. At the Dawn of Man, the souls attached themselves to all mankind - causing fears, confusions, and problems that still plague humanity today.

The Scientology origin stories told in both "Going Clear" and "South Park" are almost identical. The only glaring difference is that "South Park" portrays the aliens as looking non-human, while "Going Clear" says they looked exactly like people.

"Trapped in the Closet" was written and directed by "South Park" co-creator Trey Parker, and led to the show taking a lot of heat as Comedy Central delayed its airing allegedly in fear that Tom Cruise or the church would turn to litigation against the network. (The network and Cruise's reps have denied this.)

Isaac Hayes, the voice of Chef on the show and also a Scientologist, quit the show once he learned what the episode would be about. 

The Church of Scientology has not denied the stories of its beliefs, and L.Ron Hubbard even gives a narration of the tale in "Going Clear" via a past recording.

"Going Clear" airs on HBO March 29.

Here's the full clip from the "South Park" episode.