When it comes to the threat of Islamist terrorism, no one doubts the role of radicalisation. The internet, hate preachers such as Anjem Choudary and Abu Hamza, and the western-armed, extremism-exporting state of Saudi Arabia: all play their part in radicalising the impressionable. When it comes to the far right, however, this consensus is absent. The reason for this is as obvious as it is chilling: the hate preachers, recruiting sergeants and useful idiots of rightwing extremism are located in the heart of the British, European and American establishments. They are members of the political and media elite.

Less than two weeks ago, dozens of Muslims were murdered in Christchurch. Before the lethal rampage, the shooter is said to have inscribed “For Rotherham” on one of his gun magazines – in reference to the English town’s grooming scandal. In Britain, far-right terrorist attackers have ranged from David Copeland, who detonated a nail-bomb in a Soho gay pub in 1999 after decades of media hatemongering against LGBT people, to the murderer of Jo Cox, to Darren Osborne, who ploughed his van into worshippers outside a mosque. As one radicalisation expert, Abdul-Azim Ahmed, of the Centre for the Study of Islam in the UK at Cardiff University told ITV news, Osborne’s extremism “also came from the mainstream media. It came from mainstream politicians both here and abroad.”

Days before the Christchurch atrocity, I interviewed Tore Bekkedal, a young Norwegian socialist. In 2011 he survived a massacre of his friends at the hands of the far-right terrorist Anders Breivik by hiding in a toilet. For 90 minutes, he heard the shots and the screams of 69 people being murdered. “I call it the ‘Hurricane Breivik’,” he told me, “because people are more comfortable treating it as a natural disaster.” The anti-immigration Progress party (Fremskrittspartiet) is now a junior partner in Norway’s coalition government, he notes. As newspapers such as the Telegraph noted at the time, Breivik’s justification for his slaughter was to make “a future Europe safe from the tyranny of cultural Marxism and of Islam”.

This week the Tory former Brexit minister Suella Braverman declared: “We are engaged in a war against cultural Marxism.” When my colleague Dawn Foster challenged her, noting the phrase’s far-right antecedents, including its link to Breivik, Braverman doubled down. As the Board of Deputies of British Jews put it, “the term ‘cultural Marxist’ has a history as an antisemitic trope”. This is correct, but Braverman did not have to voyage into the darkest recesses of the internet to happen on the phrase.

“Cultural Marxism is running rampant,” wrote Sunday Telegraph editor Allister Heath last year. Other writers who have deployed the term include Sherelle Jacobs, the Daily Telegraph’s assistant comment editor; the newspaper also published an anonymous civil servant who said: “There is a strong presence of Anglophobia, combined with cultural Marxism that runs through the civil service.”

Or consider the Times, supposedly a paper of record, which has published Tim Montgomerie bemoaning the prospering of “cultural Marxism”. Or Rod Liddle in the Sunday Times, who believes young Britons are brainwashed by the “delusions of cultural Marxism”. It’s not clear whether these people were aware of the phrase’s loaded nature – they surely should have been more careful – but many readers would certainly have heard a dog whistle.

As Britain’s own counter-terrorism chief said last week, mainstream newspapers are helping to radicalise the far right with irresponsible reporting. This should be self-evident, but sometimes stating the obvious is a revolutionary act. Much of the British press incites hatred against minorities, not in fringe mosques or on street corners, but to millions of people. “Muslims tell British: Go to hell” proclaimed one Daily Express front page. Or consider a front page of the Sun, which declared that “1 in 5 Brit Muslims” had sympathy for jihadists, accompanied by a picture of “Jihadi John” wielding a knife. Months later, it was forced by the Independent Press Standards Organisation to print a statement acknowledging that its claims were misleading.

Consider the Times, which published an article by Melanie Phillips declaring that “Islamophobia is a fiction to shut down debate”, and had to print a correction after claiming that a “white Christian child” had been forced into foster care with a Muslim family. Again, as the Muslim Council put it, it was “too little, too late”. Or the Spectator, which has published defences of Greek neo-fascists, articles claiming that black people have lower IQs than white people, and a piece that stated “there is not nearly enough Islamophobia within the Conservative party”.

None of this is to deny there are many good journalists working in Britain. But too many of those working in the British press act as hatemongers who play with matches then express horror as the flames reach ever higher, while broadcasters such as the BBC have given airtime to far-right thugs such as Tommy Robinson. With the far right globally in the ascendancy – from Italy to Brazil – the role of the media must be urgently debated. Mainstream media outlets and politicians are directly assisting the rise of the far right. The silence must end, preferably before more die.

• Owen Jones is a Guardian columnist

• This article was amended on 4 April 2019 to remove a reference to Jo Cox’s murder being cheered by 25,000 people online. This figure was based on incorrect information from a third party