Charlie Hebdo is the leading satirical paper in France.
It is always controversial and has a fiercely secular, left-wing, anarchist point of view, none of which I share.
On the basis of the standard Voltaire perspective as I’ve set out on a far more trivial topic elsewhere, I defend their right to say what they say. I defend it against censorship. Against bullying.
And – like you, of course – I utterly despise those who resort to violence to silence those with whom they disagree.
Free speech is under threat all over the world.
Today, Paris has seen that threat in its most appalling, extreme end of that threat.
But it is not the first time that this has happened in France: a year ago, the country’s leading left-wing daily, Liberation, was attacked by a lone gunman.
As a publication that has caricatured all religions, Charlie Hebdo published the Danish caricatures of Mohamed – and its last office was set on fire.
The editor was put under police protection (the policeman who was protecting him is among today’s victims).
To pretend that there is doubt about why this happened, to pretend that there is not a profound, civilisation-threatening problem within modern Islam, is a dangerous fiction.
The killers shouted Allahu Akbar and yelled "we have avenged the prophet" after murdering (not "executing", murdering) a wounded policeman in cold blood, while he lay in the street and begged for mercy.
This terror in its purest form is a full frontal attack on freedom of expression.
This murderous strain of Wahhabist barbarism kills people for their thoughts. It kills us for our values. For our way of life.
Remarkably, modern Western society is so self-loathing that we seek to find fault in ourselves rather than others when this happens.
In Australia only last month, after a lone killer butchered people in a chocolate shop, this self-loathing was so powerful that the #illridewithyou hashtag immediately arose as a message of solidarity for Muslims across social media outlets against an actually non-existent threat of a "backlash" rather than, as one might more naturally expect, solidarity with the multiple victims and families of victims who died that day.
When these thugs murder writers and cartoonists, they attack the very freedom of speech, thought and expression which underpins democracy. We must reassert those values today.
Amongst the vivid moments I’ve seen in my lifetime, one of the most moving was the Champs Elysees, empty and still, while the American National Anthem played on 12 September 2001.
In its headline, Le Monde wrote Nous Sommes Tous Américains.
Today, we are all Parisian.
Alex Deane is head of public affairs at FTI Consulting and a former aide to David Cameron