Every society and group has taboo subjects. In our current ebonicoid style, we have the phrase, "Do you really want to go there?" This means, "Do you actually want to cross that line of taboo and bring up a subject of which we are all very well aware and which we know is dangerous?"
As I've said before, parts of the American experiment are an opus contra naturam, a work against nature. Neither democracy nor freedom come naturally to human communities. If they did, we would not need to enshrine them in Bills of Rights. To the extent that we have had these things, I think John Adams' insight is true: "Our Constitution was made only for a moral and religious people. It is wholly inadequate to the government of any other.” And a particular people of this kind as well --English Protestants-- one that had the cultural capacity to overcome tribalism and allow people different from themselves, especially in opinion, to be allowed to live, much less speak. That is a rare capacity.
One of George Bush's greatest errors was believing that everyone on earth --much less Muslims--wants the kind of liberty that Americans have. Not even all Americans want it. We want freedom for ourselves and people like us. We don't really want it for ideas or people we hate or who threaten us. Ask Mayor Nutter. Even to tolerate such folks it is a very much learned behavior.
We have varying ways of enforcing these Thou Shalt Nots. In unapologetically religious societies, we have blasphemy laws. In crypto-religious liberal societies, we have "hate speech" laws. Hate speech flourishes in Islamic countries. Blasphemy is a proud achievement of the West. Both regard each other's strictures and behaviors with horror. They are essentially the same.
In the West, we have politically correct shorthand to explain to people that they should shut up. Das raciss is my favorite, of course. If you don't agree with the idea of genderless marriage, you are homophobic bigoted H8er. If you are, in the words of the British Chief Rabbi, a "Christian atheist" like Richard Dawkins, your atheism is anti-Semitic. And, of course, if you suspect that Islam might be hugely, even fundamentally, significant in the Boston bombings, you are an Islamophobe.
Racist! Homophobe! Anti-Semite! Islamophobe! In the Universal Translator aboard the Enterprise, they all come out the same way: