The religion of 'Scientology' was founded by Sci-Fi writer L Ron Hubbard in the 1950's. Hubbard had written a self-help book called Dianetics: The Modern Science of Mental Health and when he lost the rights following bankruptcy, used the ideas in the book - along with the added concepts of 'auditing', 'e-meters' and other doctrines to start a religion. He had an antipathy towards Psychiatry, an attitude which permeates the 'Church' today.
Not all countries accept it as a religious organization - Germany classifies Scientology groups as an "anti-constitutional sect", and the French Government has classified it as a dangerous cult. Many adherents who have left the organisation report cult-like structures, threats of and actual violence towards apostates or critics. There are accusations of simple money-making scams that require believers to invest more and more in useless 'auditing' in order to become 'clear' - clear is a synonym for the removal of bad memories or 'Engrams' (Scientology has a huge list of jargon for its practices)
Believers are drawn into paying more and more to attain 'levels', the ultimate is 'Operating Thetan', similar to Nirvana or enlightenment in traditional religions. Once there they learn the secret creation myth: Xenu, the galactic ruler, fearing being overthrown, drugged billions of galactic citizens (or Thetans) and transported them to Earth on spaceships that looked like DC-8 aircraft. Once on Earth their drugged bodies were placed around volcanoes. Hydrogen bombs were then detonated inside the mountains killing billions. It is these Thetan 'engrams' that cling to the souls of the survivors (modern humans) causing them great harm.