I had a rather embarrassing encounter in a public lavatory on Preston railway station a few weeks ago.

As I was walking in, two young Asian men were walking out. They were in their late twenties, dressed in casual clothes and were looking at one another with some perplexity. It was only when I got inside that I realised why.

A similarly-aged white man was standing in front of the mirror and looking back into the room. He was combing his hair and speaking loudly but without any trance of frenzy or rage. Indeed, it was precisely his voluble calmness that was chilling.

“F*****g b*****d Muslims,” he said. “Eyeball me? Look at me again and I’ll send you back to whatever God you f****** believe in. Preston – breeding ground of Muslim terrorists.”

I did what every timid English male does in such circumstances: avoided making eye contact, avoided appearing as if I were listening to him at all, and left as soon as I could.

It was a ghastly but revealing encounter. I know about Islamophobia, but witnessing such controlled hatred in the flesh was something else. It brought it home how deeply, passionately and scarily some people in Britain hate Muslims, and how important it is not to pretend otherwise.

I have heard some people say that the recent terrorist murders and the barbarities of ISIS in Syria are nothing to do with Islam. With all due respect, that is clearly not true and a good example of how intelligent people can believe silly things. The extent to which they are legitimately connected with the differing traditions of Islam in the modern world is highly debateable, most of us hoping that the answer offered by many Islamic scholars – ‘not at all’ – is the right one. But there is a debate to be had here and pretending otherwise will not help anyone.

But – but – that debate is for the discursive settings that make up civil society: newspapers, journals, public meetings, seminars, lectures, blogs, vlogs, discussion groups, cafés, pubs. It is even a discussion for Select Committees and debating chambers. But it is not for the big political stage, where declarative statements are made by elected and representative officials. Because as soon as any significant political representative suggests that that terrorism, or crucifixion, or mass murder might have something to do with Islam, those like the man I encountered in Preston would ignore any ensuing debate or qualifications or nuance and simply find authoritative legitimation for his hatred, which would bring it one stage closer to violence. In other words, irrespective of what they believe, our political leaders must perpetrate the noble lie and say that these events have nothing whatsoever to do with Islam.

And this is why Donald Trump is so dangerous. This is not, of course, news. When Dick Cheney publicly condemns you, you know there is something wrong. (Expect a press release from Hades some time soon.) The idea that he is representing the views of millions of ordinary Americans – which he clearly is given how his intemperate outburst seems to boost his popularity – is no excuse. Indeed, it is precisely the reason why he shouldn’t say them, as the very act of political representation grants legitimacy to that which is being represented. Someone who says the kind of thing about Muslims that Trump has and seeks high office is not only unpleasant but dangerous, a hate crime waiting to happen.

Nick Spencer is Research Director at Theos | @theosnick

Image by Darron Birgenheier from flickr.com, available under this Creative Commons Licence