"Because it is. You might not be religious, religion - particularly the organized kind - might have its flaws, but using phrases like "mass hysteria" or "brainwashing" or "fantasy" to descibe *all* religion is just obnoxious."
Why is that? Just exacly what is the difference between believing that thetans are locked in your body and that an invisible, all powerful, omnicient man who lives in the sky caused a virgin to give birth? The bible is full of "fantasy" like this it's also full of unspeakable acts of horror. Sure christians like to disregard any part of the bible they don't like (which IMHO also gives me the right to ignore any part of the bible I don't like BTW) but you can not deny that they are a part and parcel of your religion.
Example. Christians routinely point out that homosexuality is a sin according to the bible but they never quote the second part of that sentence which states that the punishment for homosexuality is death!.