The bodies were still lying amid the rubble: some were living their final minutes; others were left horribly mutilated. Moments earlier they had been wandering around a mundane airport departure hall, full of the sounds of chattering, suitcase wheels against the floor, urgent phone calls, parents remonstrating with children.

Yet within minutes of news coming through that fundamentalist thugs had targeted random civilians for murder, the Telegraph columnist Allison Pearson was not thinking of compassion, or despair, or even disgust and fury at the culprits. Her mind turned to the thought that the atrocity could be used as a political prop in Britain’s referendum on European Union membership. Pearson tweeted: “Brussels, de facto capital of the EU, is also the jihadist capital of Europe. And the Remainers dare to say we’re safer in the EU! #Brexit.”

There is much to debate about the Brussels atrocity, but for it to be gleefully and so swiftly seized upon as convenient political fodder for the EU debate is macabre. Nigel Farage, the Ukip leader, retweeted Pearson approvingly, and Mike Hookem, the party’s defence spokesman, could not believe his luck. Though at least offering condolences to the victims, Hookem swiftly blamed the Schengen agreement “and the EU’s open door policies”. A Mail Online columnist declared: “Next time you hear someone say we are safer IN the EU – remember Brussels.” And in an astonishing removal of guilt from the terrorist murderers, added: “Merkel – and her ilk – blew up Brussels.”

I will vote to remain within the European Union, even though I am critical of its current incarnation and want to change it. At the same time, I reject the use of Project Fear by the government to frighten people into staying within the EU, backed by corporate titans warning of economic apocalypse if the vote swings the wrong way.

But those seizing on the Brussels atrocity as an argument for Britain to leave – largely based on the symbolism of EU institutions being based in the city – have abandoned any moral authority to protest about a campaign of fear.

They are arguing that remaining within the EU means you and your family are at heightened risk of being murdered by terrorists. This is illogical. Four Yorkshiremen were behind the 7/7 attacks; two east Londoners from Christian families murdered Lee Rigby. The atrocities in Paris and Brussels are largely the work of people born and raised in France and Belgium, often from families repulsed by the ideologies of their sons.

‘The peddlers of fear are playing a dangerous game’. Armed police patrol at Heathrow airport following attacks in Brussels. Photograph: Steve Parsons/PA

The peddlers of fear are playing a dangerous game. If the British people decide to leave the EU, it should be on the basis of an informed debate – one that they are not currently being offered. It is important that they make a decision in the belief that the interests of the country, and their own futures, would be better served outside the EU.

What if, on the other hand, the country leaves in part because people fear that the risk of terrorism is increased by membership of the EU? How could this be construed as anything other than a dramatic victory for terrorism, encouraging rather than deterring would-be fanatics?

In the US, the racist demagogue Donald Trump blames the Brussels atrocity on Europe’s immigration policy

Others are pursuing this avenue, albeit with more subtlety than those ghoulish interventions. In the febrile post-Brussels atmosphere, the former MI6 head Richard Dearlove suggests that Britain could be safer outside the EU, an argument echoed by the London mayor, Boris Johnson.

But it’s not just about Britain: the very long-term existence of the EU is now being openly debated, and every terrorist attack is portrayed as yet another blow to the European project as a whole. If terrorists believe they could help bring the entire EU crashing down – acting as the catalyst for the greatest chaos unleashed across the continent since the end of the second world war – then even the most sophisticated intelligence-gathering operation will struggle against their determination.

And then there’s the hatred. Last November Nicolas Hénin, a French former hostage of Islamic State, wrote in these pages: “They will be heartened by every sign of overreaction, of division, of fear, of racism, of xenophobia.” All too few listen to him; instead they follow Isis’s script, becoming the puppets of a murderous organisation they detest.

One individual in Croydon has been arrested after claiming in a tweet to have “confronted a Muslim women [sic]” to demand that she “explain Brussels”. She replied: “Nothing to do with me” – which he judged “a mealy-mouthed reply”. Then he added: “Who cares if I insulted some towelhead?” Collective guilt imposed on Muslims is not only bigotry: it vindicates Isis’s claim that the west is at war with Muslims, that they are unwelcome.

There are more examples. At a housing meeting in Hornsey, north London, this week, the tenants campaigner Jackie Peacock spoke of two Syrian refugees fleeing Isis violence: first they settled in Manchester; then, unable to find work, they came to London. When the pair complained about an allegedly poor landlord, he reported them to the police – for being Isis members.

The Labour candidate for London mayor, Sadiq Khan – who faced death threats because he voted for gay marriage – is subjected to a dog-whistle campaign falsely attempting to link him to Islamic extremists. The lesson? That even the most progressive, secular, pro-LGBT Muslims have no place in political life. It will undoubtedly be to the quiet satisfaction of the fanatics.

In the US, the racist demagogue Donald Trump blames the Brussels atrocity on Europe’s immigration policy, while his fellow Republican candidate Ted Cruz demands special patrols for Muslim communities to stop them being “radicalised” – a policy guaranteed to do the opposite.

My fear is that Isis is winning, that it is succeeding in its aim to spread fear and hatred around the globe. It is threatening to cause chaos and fundamentally change our way of life – but whether we let Isis do that is our choice. At the very least, in the context of the EU debate, Isis should not be allowed the role of a political player. If we leave the EU, then so be it. But let it not be because Isis drove us to it.