Bernard-Henri Lévy sits in the library of Maida Vale's magnificent Victorian Sephardi Synagogue waiting to deliver a talk on his latest book, L'Esprit du Judaisme, a celebration of Jewish thought.

The venue is appropriately grand: the synagogue was built in glorious mock-Byzantine style and was designed to accommodate the increasingly confident and upwardly mobile Spanish-Portuguese Jewish community as it moved from the East End of London at the end of the late 19th century. But "BHL" - as he is affectionately known - is unwell.

He cuts a diminished figure at one end of a giant conference table and he struggles with his breathing as he begins to talk.

The interview with the JC takes place on the day of the Brussels atrocities and I wonder if he is a little preoccupied - concerned, even - that his own forthright opinions on radical Islam would make him a target here tonight. In 2009 his name was found on a hitlist compiled by a Belgian-based Islamist group.

He laughs: "No. I have just finished making a film in Iraqi Kurdistan. I travelled 1,000 kilometres with my camera on the frontline between Daesh and the Kurds. I filmed the war, some battles. You think I would be afraid to speak at an event at this gorgeous synagogue, in London which I love so much? That's a joke."

Jean-Paul Sartre was stupid to say that a Jew only exists in the eye of the antisemite

He may be a little under the weather on this occasion, but France's best-known and most controversial public intellectual has clearly lost none of his appetite for cerebral battle.

From the opening paragraphs of L'Esprit du Judaisme, he takes the argument to his enemies: the antisemites, the extreme right, the Islamo-fascists.

We are used, perhaps, to a more defensive approach to questions of Jewish identity, but instead Lévy talks of "the glory of the Jews". It is a resolutely positive approach.

"It's just the way I am," he says, leaning back in his chair and relaxing into the subject. "I am, as I say in the book, an affirmative Jew. I have always thought Jean-Paul Sartre was stupid to say that a Jew only exists in the eye of the antisemite.

"The denial of self has never protected the Jews. On the contrary: it has exposed them. And in the end I believe that the affirmation of Judaism is important, not just for Jews, but for the nations, for the whole world. If the world was deprived of that, things would be even worse than they are now."

Here, in one answer, is something of the essence of Bernard-Henri Lévy, a man confident enough in his personal model of the politically engaged philosopher to take on Jean-Paul Sartre himself.

Since he first emerged as one of the French "New Philosophers" in the late 1970s, BHL has always been an iconoclastic figure, initially challenging the French left's love affair with Marxism, while resolutely insisting on being considered a man of the political left. His taste for engagement on the global stage and avowed anti-totalitarian politics drew him to support Western intervention in the Bosnian conflict.

More recently, he was directly involved in the negotiations which prompted French military action in Libya. I wonder if he has regretted his involvement after Libya's subsequent unravelling.

"Absolutely not," he says. "And even more when I see what happened in the places where we did not intervene like Syria, thanks to the British MPs and thanks to Barack Obama. The result of that is what? A country emptied of its inhabitants, a flood of refugees which is destroying Europe and the birth of a monster which is called Isis. This is the result of non-interventionism."

There is a moment in Levy's new book where the writer admits a moment of despondency and doubt about the apparent resilience of hatred for Jews. "Maybe it's too late," he says. "Maybe they will never like us."

Do events such as Brussels gnaw away at his "affirmation"? He insists Brussels was not fundamentally about antisemitism, despite the anti-Zionism at the heart of violent Islamist movements.

My question sets off a lengthy riff: "It's the purest form of nihilistic hate. It's hate for everything that lives. It's hate for everything civilised. It's hate for the citizen. It's hate for the city dweller."

He pauses for a moment and then repeats, for emphasis: "Civilised, citizen, city dweller. It's what I call 'urbicide' in the book: the hatred of cities. This is a modern version of a very ancient hatred of cities which is at the heart of all fascisms."

Lévy draws a slightly laboured breath before turning his attention to the UK and the role it plays in promoting "the new antisemitism".

He suggests there are two ways in which this country is implicated: the first in its support for the BDS movement and the second in the alliance of parts of the left with radical Islam.

On the latter he is particularly critical, suggesting that the British left had fallen for the trap of tolerating the jihadist language of some Muslims because they are perceived to be oppressed.

"Not because they share these views but because they believe it is a stage that will be bypassed. But it won't. They are making an alliance with the worst of the worst."

Such thinking was in a minority on the French left, he felt. I asked what he made of Jeremy Corbyn in this context.

"Jeremy Corbyn is difficult to imagine in France. It was different 20 years ago. Twenty years ago we had a lot of Jeremy Corbyns and you had Tony Blair. Now it's the reverse. We have Tony Blair, who is [French Prime Minister] Manuel Valls, and you have Jeremy Corbyn."

Despite his warnings about Britain's role in stoking antisemitism, Bernard-Henri Lévy counts himself an Anglophile, something he traces back to an early love of the novels of Britain's only Jewish Prime Minister, Benjamin Disraeli.

"I have respect for Disraeli. But more than that, I have respect for England and Queen Victoria. And not just because he was a Prime Minister for so long. Right up until the end of his life, he was a great dandy, an icon. He was a lion."

I ask if he himself identified with Disraeli and, for once he is silent for a while. "I never thought of that," he says. And does he attribute any of the hostility towards himself to antisemitism? "I don't know
and I don't care. Those who hate me, why they hate me, it is their problem. They have to deal with it."

So how does Bernard-Henri Lévy think of himself? His book on Judaism begins with the following statement: "There are powerful reasons, for a Jew of my kind, to despise this leprosy of the sprit which is antisemitism."

So what is a Jew of his kind? "A proud Jew. Positive. Affirmative." He adds that he believes there are grounds for optimism, not least because the new antisemites are of such a low calibre.

He uses the examples of French antisemitic writers Louis-Ferdinand Céline and Maurice Barrès. "These were horrible, disgusting characters, but they were great writers and this made them more dangerous.

"The antisemites of today are just nuts, which makes the situation for Jews not so bad. To be faced with enemies who are nuts or ill-educated is better than having enemies who are geniuses."

L'Esprit du Judaisme emphasises the gift Judaism can give to the world. It is uncompromisingly outward-facing and, although it necessarily discusses antisemitism, it is not a book about the hatred of Jews. It is a deeply generous book that resists introspection.

This is something the philosopher also expects of his non-Jewish comrades on the global anti-totalitarian left. "The French, the British, the Americans who aren't implicated in antisemitism, I don't speak about it with them. We speak of our mutual struggle: the struggle for human rights, for universal human values and what Judaism can bring to that struggle."