Which brings us onto Donald Trump. Last night Donald Trump announced a new ‘policy’ idea which would be to stop any more Muslims going to America. He would even, it seems, prevent Muslim Americans who are currently out of the country on their holidays, from returning home. This is – it need hardly be said – a back of the envelope policy. And it has already had the desired effect. The social justice warriors who mistake Twitter for real life, have been busily signalling their utter outrage at Trump’s remarks. Journalists have seized the opportunity (which the New York Times and others have been trying all along) to insinuate that Trump is in fact the new Hitler. The reaction is as ill-tempered as the original comment. But we should know how we got here.

When the political left refuses to identify where Islamic terrorism comes from, what drives it or what it can even be called, it leaves the ground wholly open for anyone else to do or say anything they want. Far from being blunt tools or broad brushstrokes, referring to ‘Islamic extremism’ or ‘Islamism’ makes an obvious and conscious effort to put down a delineating line between non-extreme Muslims and the extremists from their faith. Yet many Muslim organisations, among others, reject this. Groups like the Council on American Islamic Relations (CAIR) expend all their energy berating anyone who makes this delineation and pretends that people exercising such care are in fact ‘tarring all Muslims’. What such Muslim groups seem not to realise is that this in turn makes people suspicious of all Muslims. ‘Why are these Muslim groups pretending that any and all critics of the jihadists are saying something they are not? Maybe all Muslims are in fact jihadists?’ is a conclusion some people will find themselves pushed to.

It is the same with the question of immigration and demographics. In recent decades left-wing opinion has worked to make it impossible to discuss such issues without being called a ‘racist’. Worrying about what percentage of Muslims might be extreme or attracted towards extremism has also been turned into a ‘racist’, ‘bigoted’ and ‘Islamophobic’ discussion. Yet mass immigration from the Muslim world into liberal democracies at a time when the Muslim world is undergoing a succession of civil wars is a terrible idea. At the same time, keeping all Muslims out or barring Muslim Americans from returning home from their holidays is obviously not the solution either, not least because it would deprive decent people who are concerned about this fight of some of our most knowledgeable, brave and committed allies.

But what people seem slow to realise is that suppressing legitimate concerns and decent discussion inevitably leads to people addressing the same things indecently. We can thank the American left for the creation of Donald Trump and we can thank them for his comments last night. For years the left made the cost of entering this discussion too high, so too few people were left willing to discuss the finer points of immigration, asylum or counter-terrorism policy and eventually the only release valve for peoples’ legitimate concerns is someone saying – wrongly in my view – ‘keep them all out.’

On Sunday night President Obama broadcast from the Oval office to try to fill some of the vast void he has left open, tremulously approaching the possibility that radical Islam exists. But his principle concern seemed to be not that primary problem, but rather the possibility of this ‘dividing’ America. The speech was weak and ill-thought through, but in any case it is too late for him to row back now.

In Europe I have said for more than a decade that if political leaders kept saying ‘Islam is a religion of peace’ and similar untruths and half-truths then a day would come bearing an atrocity so bad that the mainstream politicians would not be listened to anymore. This prediction is currently being played out across the Channel in France. In the UK I am happy to say that the Prime Minister and those around him have been listening. They realise that a complex problem does not have easy answers. It does not have easy answers like pretending that ‘Islam is a religion of peace’. And it does not have easy answers like those of Donald Trump.