Both theism and atheism are faith based positions.
Atheism is a faith based position as much as not collecting stamps is a hobby. Simply not believing in a god doesn't require faith. It is just refusing to believe in something for which there is no evidence.
Not true. In order to disbelieve something, you have to believe in the premise that it does not exist. You have no undenyable proof that a thing does not exist, therefore you are believing it does not exist. You may have good evidence which suggests that a thing does not exist, which means that it may be a reasonable leap of faith to believe it does not exist, but it still involves a conviction without proof. Without absolute proof of a negative, the best you can have is a logical assumption, not a logical certainty, and an assumption still takes faith. It's not illogical to say "There's no reason to beleive in god." It is illogical to say "There is no god". The first is true. The second is speculation. Probably good speculation, and I'm not discounting its possibility, but it is true that there is not concrete evidence to support the existance of god, while it is not true that there is concrete evidence to support the non-existance of god. Only probable evidence that supports the non-existance of god.
You're not considering a key fact of the known practices of Scientology. They have been known to violently oppose anyone that openly disagrees with their views and beliefs, and they are also well-known for propaganda and orchestrated operations by its members to influence media. Keep in mind that the protest group, Anonymous, wears masks to protect their identity for fear of CoS members harassing their homes and businesses, as this group has a history of organizing its members to forcefully influence people to either follow them or stay silent.
On a system like Wikipedia that is user-edited, it easily allows for an organized group of a certain belief system to enter their own set of beliefs and through sheer numbers, override the other peers writing to the articles. There simply aren't enough people working to correct misinformation on Wikipedia to constantly correct changes made by the Church of Scientology or any other concerted effort to add propaganda-like entries into articles.
Combine their pentiant for organized propaganda and Wikipedia's vulnerability to misinformation and it just makes sense to ban their posts, not because of a difference in beliefs but in prevention of having a vulnerability exploited.
Disc space -- the final frontier!