Why can't religious study in "all" schools, even private schools, be made illegal?  ?

I'm sorry to hear your personal experience with religions has been that bad. And I agree that it's bad. 

But it's not representative of most religious beliefs and practices. And you've failed to consider the consequence: without beliefs--that is, working assumptions to deal with cases in which the truth cannot be proven--there is no basis at all for judging for ourselves what is right and what is wrong. 

You yourself evidently hold such beliefs, or you wouldn't have written as you did. And although I've got a lifelong background in one religion (and some exposure to others), your beliefs aren't that much different from mine. The sort of crap "religious" behavior you've described seems just as wrong and stupid to me as it does to you. 

But that is our belief. We can't prove it. And if any one set of beliefs, even ours, is imposed on everyone else, then nobody is free to think for themselves and reach a better belief system. What you propose would merely impose a different orthodoxy, which might not refer to itself as "religious" but would still BE an inflexible, unthinking belief system forced on others. 

I'm not against stopping the sort of crap you describe. But in the long run, it cannot be stopped by force; it can only be stopped by persuading people to think for themselves, and choose something better. No form of totalitarianism is improved by the awfulness of whatever it picks to oppose, and in fact most totalitarian regimes do their best to invent more awful descriptions of their opposition, as a basic exercise of propaganda.

That's why private schools are called "private". They don't receive funding from government sources, and therefore are not subject to government control. And students in private schools consistently receive far more scholarships to leading colleges than graduates from public schools.

In extreme cases, such as this, deprogrammers are called in.

The only religious study that should be allowed in schools is a study of comparative religions.

At the same time, Netflix is featuring a true to life, fully documented story of a miracle, where a man's entire hip (which had been totally consumed by cancer) was miraculously regenerated, at the Marian Shrine, in Lourdes, France. 

It can be, of course.

See: Maoist China, for example.

BECAUSE THIS IS A FREE COUNTRY!! WOULD U RATHER BE IN CHINA??

Religion is part of society, outlawing religious studies would be like outlawing cooking or sports or stamp collecting or everything else that is part of human society.

You would have to outlaw fiction, poetry, philosophy, drama, and comedy as well.

Because that's what happens in fascist and communist States. If you want that kind of oppression you should move to China. 

Because of the First Amendment. It is literally the first sentence... "Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof;"