I have thought long and hard about this one. I grew up having been subjected to two mutually exclusive tenets of secular culture:
1) Freedom of speech is an absolute good.
2) The Holocaust could have been prevented had Nazi propoganda been prevented.
It is amazing how the second has become far more dominant in politics lately. I have little doubt that had it been other than the Christians who have felt the curbing of speech more than any other group I probably would never have come to question the politics of (2). But Providence works in these ways to teach, I guess.
Last year in my apologetics class I had the class read a couple articles on this topic, since the freedom of expression and of religion are certainly important topics today. The articles were generally from a legal perspective, a discipline of which I know nothing more than what I can glean from Law and Order. They were, apparently, learned writings, but I found in them very little to check my growing libertarian tendencies.
It seems to me that a legal system should be consistent in its application of philosophical principles. Either the legal system is set up to protect a specific value system or it is set up to repress criminals. I understand the second to be defined as that 'swinging of the fist that impacts upon my neighbour's nose,' and no further. The law should clearly state which it is about. In the West today we have a conflation of the two kinds, and this allows groups to act in contravention both of the concrete good (the first kind) and the neutral good (the second kind).
I am used to thinking of the good state as that which seeks to impose no one's concept of the good upon others, but protects people from anything but the most crucial application of force. The democratic system is good, not because people will naturally choose the good on their own, but because it is set up to impede others from imposing their idea of the good upon me. They must operate in the realm of persuasion in the open forum of discourse, not by force.
Now, of course, it is philosophically absurd to say that a system is better which impedes the good. But with people we are not talking about the good per se, we are talking about conceptions of the good. How tempting it is to move from one to the other, though. How easy to say, since Christianity is better it is a better system which favours Christianity. How easy to say, since a culture without prejudice against homosexuals is better, such a culture should be forcibly created. But the unphilosophically enlightened who sought to impose Christianity in times passed are reborn as homosexualists who seek now to impose their new philosophy. Anyone but the imbecile realizes that a certain agnosticism is required in the wiseman. This is the strongest argument for limited government, limited government involvement in education, in media, etc.
Which means that my fist must tolerate pornography, atheism, blasphemy, racial hatred, etc.; it does not, however, mean that my tongue must. I think this is the better way. I'm still thinking about it, though, because, that is what a human being ought to do.