"there has to be some authority who decides whether someone was justified in vandalizing a cinema, or whether they should be arrested for it."
Come on, let's limber up the old thinking muscles, here. Ready? One-two, one-two, one-two. Okay, now, take one step deeper into the process from "there has to be some authority."
What is the one thing that trumps property rights? The right of other people not to be harmed by exercise of those property rights.
That's why you can't just build a swimming pool in your front yard with no fence around it. Sooner or later somebody's two year old is going to toddle over and drown in it. It's called a "public nuisance."
So--we have a right not to be harmed by the cinema owner's use of his private property. Who says so? God says so. Government says differently? Then **to hell with** the government. The government is wrong. When the government is wrong, then measures up to and including overthrowing it through force of arms are justified. That's why we have a Second Amendment to the Constitution: so that the people would be armed in case they needed to replace the government.
"In the case of the colonists, they knew they would get in trouble with the authorities, but they did it anyway."
Yes, based on the thinking I outlined above.
You seem to be thinking in terms of government being the solution instead of the problem.
"So, to clarify: are you saying that people who vandalize cinemas in what you see as a good cause should be arrested, but given moral support by those who agree with their cause? Or are you saying that if people vandalize in a good cause, they should not be arrested for it?"
You mean from a moral standpoint? Of course they should not be arrested. What should happen is that the government and the theater owner should take it as a warning and temper their abuses.
I agree with your comments. For some reason, a segment of the population (at large, and here on FR) don't [want to] see that evil actually exists and it does and will harm people irrevocably. Futhermore, their argument is that "if you don't like homosexual porn films, don't watch them". It's the same argument as "If you're against abortion, don't have one". To carry it further: "If your're against arson, don't burn up buildings or forests". Etc.
The problem with promotion or tolerance of sexual immorality, is that it creates a society of broken people. Even if you or I or someone else tries to live moral lives, the atmosphere affects everyone, especially children. So we are all affected. It's like living in a landfill - if you live right in the middle of a garbage dump, even if you keep your own house clean, the stench, flies and rats will get into your house too.