Freedom of speech and terrorism

On a day when French police are still hunting for the killers who murdered journalists at the Paris office of a satirical magazine, probably because of the magazine’s publication of material mocking Islam and Muhammad, is there anything that can be said about law and religion issues for Australia?
The support expressed for freedom of speech in the wake of this terrible event is real and important. But there are of course important questions about the limits of free speech.
“Freedom of speech”, like any other human right, is never and has never been absolute. We restrict speech where it causes physical harm to people (such as an incorrect health warning on medication, or the classic example of someone who shouts “fire” in a crowded theatre and causes death and injury in the resulting stampede.) We also make some speech unlawful where it incites direct violence against others, or falsely destroys someone’s reputation ( through the law of defamation.)
Here the speech of the magazine in mocking sacred Islamic topics will have led, and foreseeably so, to distress and offence among some Muslim people. Indeed, when the original Danish cartoons were published, there may well have been some who were physically injured in subsequent riots, which again were reasonable predictable. Does that mean we should pass laws making it illegal to cause such offence on the ground of religion? It may be that once the current outrage has subsided to some extent, there will be calls for such laws to be enacted or enforced more vigorously.
In my view, this would be a bad idea. I think that there is some limited scope for so-called “religious anti-vilification” laws, provided however that those laws are carefully crafted to only catch speech which incites hatred or violence against persons of a particular faith. But the law should not prohibit the mere causing of “offence”, nor should it restrict robust debate about the truth or falsehood, or good or bad effects, of religions. I make the case for this in a paper which can be downloaded here.
Those who commit violence in the name of offence should be caught and dealt with according to law. It may never be possible to prevent such actions altogether. But we should not restrict freedom of speech in discussing religion because of a fear of such response.