Since there's no known cure for religionism putting them in mental hospital wouldn't work.
No known cure? Then why is it that numerous religious people (including former fundies) have become atheists. Case in point: Matt Dillahunty from the Atheist Experience who was even studying to become a preacher before he deconverted.
Suppressing the vile hate-speech of religion isn't censorship.
Suppression of speech IS censorship. I think the dictionary you are using is broken. Go buy a new one.
They have nothing legitimate to say.
Nothing? Really? "Love thy neighbor as thyself" is not legitimate? Granted, you don't have to be religious to follow that or something like that and religion doesn't have a monopoly on these nuggets of wisdom but there are some in there and to say there aren't is pure propaganda. There's enough wrong with religion; we don't have to resort to lying about it.
Nothing else has worked.
Bullshit. The problem is that different people respond to different approaches (i.e. some respond to logic, some to moral arguments, and some to various combinations of approaches and the challenge is to find those approaches. Or you can take the lazy way and just stuff 'em in jail and then prepare to deal with the international backlash, your choice.
The families are better off without a religionist influence around.
So you think an orphan with both parents in jail is better off than a child raised in a religious home?
Unlike adults children might be curable.
The expression "you can't teach an old dog new tricks" is utter bullshit. While there are some people that are so far gone that nothing will ever get through to them, most people are not that far gone and can still be reasoned with or at least emotionally swayed. I personally know people who deconverted even into their 50s or 60s. Now, granted, statistically people tend become more conservative as they age, that doesn't mean it's impossible to get through to them, it might just take a bit more work and a more nuanced approach.