Where to begin..
Scientology is not a religion - except for tax purposes. I realize that in your view that’s a feather in its cap.
The “Enlightened” French Terror was quite demonic as was the “secular” Stalin and Mao.
To compare the French Terror, which lasted fourteen months, in scope or duration to the depredations of either Communism or Christianity is to betray an ignorance of history so thorough that it's no surprise you have no idea where to begin.
As for Scientology not being a religion, I'm sure to a practitioner of some other silly nonsense it doesn't seem like one, but it is. Body Thetans are no stupider (or any more real) than demons, angels, or the Easter Bunny. Hubbard may not have been sincere in his belief in these things, but Tom Cruise and others like him are. That parallels the development of plenty of "spiritual" mumbo-jumbo over the ages.
In my view, the tax deduction granted to all the businesses that call themselves "faiths." Ought to be abolished.