If you accept -- and I do -- that freedom of speech is important, then you are going to have to defend the indefensible. That means you are going to be defending the right of people to read, or to write, or to say, what you don't say or like or want said.
....
And in each case ... that was the point of view of the people who were banning these works or stopping people reading them. They thought they were doing a good thing. They thought they were defending other people from something they needed to be protected from.
...
the only answer I can give is this: Freedom to write, freedom to read, freedom to own material that you believe is worth defending means you're going to have to stand up for stuff you don't believe is worth defending, even stuff you find actively distasteful, because laws are big blunt instruments that do not differentiate between what you like and what you don't, because prosecutors are humans and bear grudges and fight for re-election, because one person's obscenity is another person's art.
...
Because if you don't stand up for the stuff you don't like, when they come for the stuff you do like, you've already lost.

(c) Neil Gaiman, Why defend freedom of icky speech?, 01.Dec.2008
http://journal.neilgaiman.com/2008/12/why-defend-freedom-of-icky-speech.html