The obvious sign that the Church of Scientology controls the minds of its members is that Scientologists can never disagree with L. Ron Hubbard about anything. Hubbard is effectively infallible, without ever calling himself infallible. Anyone in a Scientology Org who has disagreements with LRH gets handled. The first step in handling is to look for misunderstood words. If none are found, the next step is to look for evil purposes on the part of the person who dares to disagree. And if that does not resolve the disagreement, then the person must be suppressive and is deemed to be an enemy of Scientology. Any non-Scientologist who criticises Scientology goes directly to the category of Suppressive Person. According to Hubbard, Scientology is only criticised by people who do not want other people to get better. So while everything else that the human race has invented can be subject to criticism (and Hubbard himself has criticised pretty much everything) Scientology could never be legitimately criticised, which of course was very convenient for Hubbard, who never had to reply to critics.

In addition, if your experience in using Scientology is that it did not do what L. Ron Hubbard said it would do, then (supposedly) you are necessarily wrong, and you must not have used Scientology correctly. This is part of the famous policy letter "Keeping Scientology Working" (KSW). This policy letter does not actually keep Scientology working, but it does serve to shift the blame for the failures of Scientology away from Hubbard and onto the individual Scientologist.

If you were to ask why it is that L. Ron Hubbard can never be wrong, you would be told that he is the founder of Scientology. That explanation misses the point. Being the founder of some subject does not confer infallibility. Every subject was founded by someone, and few founders claim infallibility other than Hubbard (other cult founders, such as Joseph Smith, founder of Mormonism, also present themselves as sources of infallible wisdom). Just to give one example, the science of physics was founded by Galileo. Physics does not, however, begin and end with the work of Galileo, nor would he have wanted it to. Physics has advanced tremendously since the time of Galileo, in ways that Galileo could not even remotely have predicted.

Scientology, however, begins and ends with Hubbard. Hubbard is the only acceptable source of truth about Scientology, according to KSW. Scientologists are sternly warned to trust no one else. Yet, that is not how any honest field of enquiry would operate. A field of knowledge is normally open to new discovery; that is how the human race makes progress. But in Scientology, there can be no new knowledge, now that LRH is no longer with us.

Thus, Scientologists cannot think for themselves, they can only think what Hubbard tells them to think, nor can they draw conclusions on the basis of their own experience, unless they have experienced exactly what Hubbard told them to experience, nor could they learn from anyone other than Hubbard, the sole source of knowledge. The mind of a Scientologist is quite well controlled.