Agnès Poirier: Even after all France has endured the attack on Nice is a huge shock

It is not often that the French president addresses the nation at 3.45am, even in a country where heightened vigilance has become the norm. A few hours earlier, the Promenade des Anglais in Nice was the scene of a massacre. Thousands of families and tourists had been celebrating the memory of the French revolution and the birth of democracy, when an 18-tonne lorry forced a security aside and mowed into the crowds , killing 84 innocent people, among them many children .

Every French person remembers the first time they set foot in Nice, and this corner of paradise called the French Riviera. As a Parisian child aged 10, accustomed to all the capital's shades of grey, what struck me immediately was the blinding summer light. And the palm trees: so many towering palms against a backdrop of perfect blue sky. I'd never seen such a sight before. As for the Promenade des Anglais, it was every bit as beautiful as it appeared in the Raoul Dufy poster I had at home.

The events in Nice make us realise that there are clear limits to what the state and its institutions can do

This is the third attack on France and the French way of life in 18 months. Everyone of us has been targeted by this radical Islamist ideology: cartoonists, journalists, French Jews, football fans, diners, rock fans, and now families enjoying that most childlike and wondrous of spectacles: Bastille Day fireworks.

While we may have got used to round-the-clock army patrols at sites throughout the country, and we may be grateful that some of our philosophers, writers and scholars get 24-hour police protection, it is still hard to bear this heavy weight on our shoulders.

Just last weekend, we were so relieved that Euro 2016 had finished without a hitch. French police could certainly have done without Russian and English hooligans, and violent demonstrations against the labour reform , but all in all, things had gone well, and we were happy that the French team had made it to the final.

But now Nice. Now what? A few hours after telling the country that the state of emergency would at last end, President François Hollande had to go back on his decision. All police forces saw their much-deserved holidays cancelled overnight, and a reserve made of retired army and police personnel was asked to take up active service in order to relieve and help exhausted officers throughout the country.

If one thing, the events in Nice make us realise that there are clear limits to what the state and its institutions can do. As the Islamic scholar, Gilles Kepel, spelt out clearly on Friday morning, this threat and the challenges it brings concerns us all, individually and collectively: "It is French society, as a whole, that must destroy the radical Islamist ideology, not just the police."

It is something I have felt from the minute I heard of the murders of our much cherished cartoonists back in January 2015 . I felt personally responsible, as a French citizen, for the death of my 80-year-old cartoonist compatriots. It was my fault for not being lucid enough, my fault for leaving them alone in publicly questioning the tyranny of religions when allowed to invade the realm of politics.

There is hope, of course, that this warped ideology, in its profound inhumanity, will eventually self-destruct. We shouldn’t simply wait for it to happen, though.

A state of emergency cannot protect us all. The aim of the attackers is to exhaust police forces while triggering a civil-war mentality in the country. The question is: what can each of us do to eradicate this festering disease? We can stay calm and resolute, of course, but that is not enough. The government must have a clear long-term strategy, and we must all be united and stand firm on the République’s values of fraternité and laïcité.

Agnès Poirier is a political commentator and film critic

Guardian News and Media 2016