Out of all the reactions to the Westminster attacks yesterday, Donald Trump Jr’s was my least favourite. After news of the terror incident broke, the 39-year-old eldest son of the President of the United States shared an article written by Sadiq Khan in September 2016 on his Twitter feed, accompanied by the words: “You have to be kidding me?! Terror attacks are part of living in a big city, says London Mayor Sadiq Khan.”

Call me crazy, but as soon as that popped up in my feed, I got the distinct feeling he wouldn't be sharing it if the Mayor of London was a man called John Jones.

For sure, there were more offensive statements than Donald Trump Jr’s out there last night. Former English Defence League leader Tommy Robinson, for instance, said what we were all expecting from him – “The reality is these people are waging war on us. This has been going on for 1,400 years and while it’s going on the police leaders and the political leaders want to invite more” – before tweeting: “Muslims make up only 4 per cent of the UK population, look at the continued chaos and destruction they cause, what do you think it will be like with 20 per cent?”

Sadiq Khan on the Westminster attack: "Londoners will never be cowed by terrorism"

And, of course, none of us were surprised when Islamophobic trolls unleashed their views across social media, proclaiming that it was time we kicked “them” out of “our country” suggesting that any normal Muslim is capable of random terror (never mind recent confirmations from the police that the Westminster attacker was both British-born and already known to MI5).

But there’s a big difference between a periphery political figure such as Robinson, and an army of disaffected trolls without any platform beyond their Twitter accounts, and a person of international influence such as Donald Trump Jr.

President Trump has embraced nepotism more than any other US leader in modern history, using his position to bolster his children’s careers and afford them a huge amount of power. Earlier this week, we learned that Trump's daughter Ivanka will be given a West Wing office, government communication devices and classified security clearance – despite not taking on a paid role or being sworn in (although she does say she’ll “voluntarily” follow the ethics code she’d be bound by if she had been).

What the Trumps say matters, in other words. And despite their love of proclaiming “FAKE NEWS” at other news outlets every five minutes, there’s something insidious about dredging up an article from a year earlier and sharing a quote from it out of context, when that article is an interview with the London Mayor and London is currently in the midst of a terror attack. It’s not exactly fake, but it’s not being truthful either.

Here’s what else Khan said in the article shared by Donald Jr: “[Combating terrorism means] being vigilant, having a police force that is in touch with communities, it means the security services being ready, but it also means exchanging ideas and best practices … Nothing is more important to me than keeping Londoners safe. I want to be reassured that every single agency and individual involved in protecting our city has the resources and expertise they need to respond in the event that London is attacked … [Terrorists] want to kill. They want to maim and terrify. It is my job to try to make sure that we are as safe as we can be.”

Sadiq Khan is one of the most prominent Muslims in British politics. He is a formidable politician, one who became mayor after being subjected to a shameful 'dog whistle' campaign that was even denounced by the sister of his opponent, Zac Goldsmith. The fact that his star has continued to rise despite many cynically attempting to ramp up Islamophobic sentiment against him is testament to his dignity in the face of malicious provocation and the progressive values of Londoners.

When your first reaction to a terror attack in London is to wrongly suggest, through selective tweeting, that the London Mayor is relaxed about terrorism and may have said so in the immediate aftermath of that attack, you are very deliberately and very foolishly playing a dangerous game.

Isis, like most militant organisations, knows that the best way to radicalise people is to put them in an environment where they have something to react strongly against. Tempting ordinary people to join a terrorist organisation is hard if you’re not recruiting from a place where suspicion, prejudice and alienation are rife. Best of all is if you don’t just pick off the loners, the misfits and the unstable, but you manage to penetrate ordinary households filled with people who easily blend in to the society you’re targeting. The first step in piquing their interest is convincing everyone else that those people are terrorist sympathisers already.

Sean Spicer: Trump has been briefed on the Westminster attack and has called Theresa May

This is the reality of radicalisation, and the simple reason why London needs a Muslim mayor now more than ever. Isis is obsessed with grandstanding and symbolism – it has long known the benefits of propaganda, dedicating a substantial amount of money and manpower to publishing magazines, releasing one-off gruesome execution videos and reaching out to potential recruits over carefully crafted social media accounts. The narrative they push is simple: the West is at war with Islam. The existence of a Muslim mayor of London symbolically destroys that narrative from the outset.

Sadiq Khan – or, as Katie Hopkins had it, “Sadiq Khan’t” the “predictable idiot” who should “think again” before penning “some naff missive about a proud city, standing together, united by shared values” – is important. I don’t state his importance because I’m into super-liberal sentimental love-ins (although I’ll take those too) but because his very existence is some of the best proof we have that Islamist propaganda is a lie. The trouble with ranting and raving against Muslims isn’t just the fact that it’s deplorable racism which should concern anyone with a moral conscience, but that it definitely doesn’t protect the West from future acts of terrorism. It is certain to make everything worse.