After so many attacks over so many years, we have become inured to terrorist atrocities. This in itself is a tragedy. Yet even after so much previous bloodshed in the name of hate-filled ideologies, the murder of 49 men, women and children at two mosques in Christchurch, New Zealand, on Friday has spread shock and disgust around the globe.

There is something particularly appalling about targeting people for their faith, as they engage in the act of worship.

But there were other factors behind our collective outrage: recognition of the spread, power and brutality of the global far right; the evidence that it feeds off a widening Islamophobia that reaches deep into our political culture; and the demonstration of how terrorism has been made immeasurably more effective by modern technology, in this case the manner in which the attacker deployed Facebook to display his gruesome work.

Expressions of solidarity and support have flooded in from all over the world. These are made in the hope that they will provide some comfort to Muslims who will be feeling even less safe after Friday’s attacks and are to be welcomed. But thoughts and prayers are not, and have never been, enough. In the weeks and months after such an atrocity – when the initial shock and grief has passed, but the extra police presence remains – we have a duty to the Muslim, Jewish and other minorities that feel under threat from far-right extremism. It is to ask a simple question: are we doing all in our power to prevent such an attack happening again?

The regrettable truth is that expressing deep sympathy in the immediate aftermath of an attack comes much more easily than longer-term reflection on the role that politicians, and social and traditional media may play in creating an environment in which far-right terrorism can flourish.

There can be no doubt that the west has underestimated the risk of far-right terrorism. The murder of the MP Jo Cox in 2016 left Britain numb with shock. Yet what lessons were really learned in the wake of her assassination? Since then, the far-right threat has only grown. In June 2017, one person was killed and many more injured after a man drove a van into a crowd outside Finsbury Park Mosque. There were a further 11 far-right terrorist attacks that year and yet more attacks were thwarted by police, including a plot by a member of the neo-Nazi group National Action to murder the MP Rosie Cooper. This is why the former head of counter-terrorism at the Met, Mark Rowley, has warned that the UK has not yet “woken up” to the threat posed by the far right.

Britain is not alone in this: in the US, the number of far-right terrorist attacks quadrupled between 2016 and 2017. Last year, 11 people were shot while worshipping at a synagogue in Pittsburgh. Yet President Trump has slashed funding aimed at reducing domestic terrorism.

There has been a tendency for our political leaders to underplay far-right violence by claiming that it is the product of isolated individuals, while seeing Muslim terrorists as linked to groups working systematically to destroy western liberal societies.

One reason for this double standard may be that it is easier to attribute organised evil to fundamentalist movements whose origins lie in societies that appear to have little in common with the west than to accept that the same evil can grow in the hearts of those who live alongside us.

But this failure blinkers us to how much far-right and Islamist terrorism have in common.

Two critical elements they share are the importance of non-violent extremist statements and ideas in radicalising those who go on to commit terrorist atrocities and the role of social media in disseminating hatred and radicalising others.

Like its Islamist counterpart, far-right terrorism is only one element of a much broader movement. When that movement is strong and empowered, so are its violent elements. Here in Britain, Ukip has embraced far-right extremism under its leader, Gerald Batten, who has described Islam as “a death cult” and has appointed Stephen Yaxley-Lennon, the far-right thug better known as “Tommy Robinson”, as an adviser. Five out of the 10 far-right activists with the biggest social media reach in the world are British. Elsewhere in Europe, populists who appeal to the Islamophobic and the antisemitic are increasing their power base: Viktor Orbán in Hungary, Matteo Salvini in Italy, Jarosław Kaczyński in Poland.

But it is not just a problem in the political fringes. Here in the UK, both mainstream parties have become infected with racist hate. The Conservative party stands accused of failing to act upon all allegations of Islamophobia in its candidates and members. Moreover, senior Tories have been complicit in spreading Islamophobia. Last year, Boris Johnson compared Muslim women wearing burqas to “letterboxes” and “bank robbers”. According to the hate crime monitors Tell Mama, this led to a rise in incidents targeting women wearing the burqa. In 2016, Zac Goldsmith’s campaign for London mayor deployed a series of racist dogwhistles to imply that Sadiq Khan had links to Muslim extremists. Not only did he face no censure, other senior Tories, including David Cameron, joined in: Theresa May said Khan was unfit to be mayor “at a time when we face a significant threat from terrorism”. Jeremy Corbyn has been so remiss in getting a grip on antisemitism in the Labour party that the Equality and Human Rights Commission has taken the extraordinary step of opening an investigation into the party.

Social media platforms and news sites have too often fallen into the trap of spreading the terrorists’ message. Hours after the Christchurch shootings, the footage the attacker streamed live could still be viewed online. Other publications have been too quick to give a platform to Islamophobic views in the name of free speech without acknowledging that with free speech comes responsibility and there may be real-world consequences to their decisions.

Eight years ago, Sayeeda Warsi argued that Islamophobia had passed the “dinner-table test” in Britain. Since then, Islamophobia and antisemitism have come to pollute mainstream politics. The link between hate speech and violent extremism may be complex and indirect, but it would be naive to dismiss it altogether. So the world faces an important test in its response to Christchurch. Will it be to express solidarity and move on? Or will our leaders make more effort to call out all forms of racist hate wherever they are found? That would be a fitting tribute to the 49 people who lost their lives on Friday.

• Crisis support services can be reached 24 hours a day. In New Zealand, the crisis support service Lifeline can be reached on 0800 543 354. In Australia, Lifeline is 13 11 14. In the UK and Irish Republic, contact Samaritans on 116 123. In the US, the National Suicide Prevention Lifeline is 1-800-273-8255. Other international helplines can be found at www.befrienders.org.