Honestly, it seems pretty simple, doesn’t it?  It’s like my mom always said, Don’t be mean.  You can always criticize, but don’t be mean.  It doesn’t seem that hard of a principle: ie, your logic is flawed, you should stop drinking, I think what you’re doing is bad for the economy rather than, you are evil, we should destroy you, etc.  I know the response: but some people ARE evil!  Maybe, sure.  But those situations are a lot more rare than current discourse allows, and such a lack of nuance makes real claims of evil much less powerful.  So, to quote my loving mother, be nice!  This is all in reference to a Dutch fellow who wants to ban the Koran, comparing it to Hilter’s magnum opus:

This seems a trifle obtuse. Comparing a book that billions hold sacred to Hitler’s murderous tract is more than an exercise in literary criticism; it suggests that those who believe in the Koran are like Nazis, and an all-out war against them would be justified. This kind of thinking, presumably, is what the Dutch law court is seeking to check.

One of the misconceptions that muddle the West’s debate over Islam and free speech is the idea that people should be totally free to insult. Free speech is never that absolute. Even — or perhaps especially — in America, where citizens are protected by the First Amendment, there are certain words and opinions that no civilized person would utter, and others that open the speaker to civil charges.

This does not mean that religious beliefs should be above criticism. And sometimes criticism will be taken as an insult where none is intended. In that case the critic should get the benefit of the doubt. Likening the Koran to “Mein Kampf” would not seem to fall into that category.