New Zealand is best known for its breathtaking wilderness, found in distant but secure islands at the edge of the world. On Friday that changed. Forty-nine people were killed in shootings at two mosques in central Christchurch in a suspected terrorist attack during the congregational prayer. The horrific events have left the country in mourning and shock. Muslims make up less than 1% of New Zealand’s population and the faith’s most prominent adherent is a rugby player. This was a stupefying amount of lethal force in a country that saw only 35 homicides in all of 2017. New Zealand as a nation will collectively have to deal with a trauma that no parent, no relative, no friend should ever endure.

At the time of writing, it is unclear whether Brenton Tarrant, the 28-year-old Australian suspected of both attacks, had accomplices. On a Facebook post last year he had called the people whom he had met while travelling in Pakistan, presumably all Muslim, “the most earnest, kind hearted and hospitable people in the world”. If Tarrant is the same man wearing military fatigues who livestreamed himself carrying out the attacks, then the humanity he had publicly recognised in others had in months been drained and replaced with hate. A Twitter account with the same name posted links to a manifesto reeking of white supremacist conspiracy theories.

The birth, growth and resilience of the far right, which once festered in dark nooks and crannies, has been assisted by the in-group echo chambers of social media. It now festers in plain sight. The manifesto, videos and photos associated with the latest atrocity have since been circulated on the web, where it is appalling to see some celebrating the attack. Too many media outlets in Britain thought nothing of dousing readers in this hateful bile. Responsible journalism must distinguish between its legitimate function to communicate information and the attempt by fascists to shut out perspectives, raise fears and heighten prejudice. The US news media, research shows, was hijacked from 2016 to 2018 to amplify the messages of hate groups. In Australia tabloids have portrayed attacks on South African farmers as evidence of “white genocide” while Sky News Australia apologised for interviewing a neo-Nazi.

Such atrocities and the trail of media posts left in their wake are designed to generate searches via racist memes and language. It is public relations by mass murder. The rise in hate speech, too readily accepted by some, is licensing violent acts. How else to explain such consistent increases? Similar dynamics lurk behind antisemitism’s reappearance. Last October the deadliest antisemitic attack in American history saw 11 people gunned down in a synagogue in Pittsburgh. This is why not only Muslims worldwide, but other minorities feel more vulnerable.

Politicians have created the swamp for such reptiles. White supremacists in America clearly believe that they have a fellow traveller in the White House. If they are mistaken then Donald Trump has hardly done much to disabuse them of this idea. Others have taken a cue from his overt race-baiting, unable even to resist the urge to whip up Islamophobia in the aftermath of the latest killings. Mr Trump could fill a bath with crocodile tears he has wept. In the US white supremacists and their ilk have killed far more people since 11 September 2001, than any other category of domestic extremist. The threat of violence from far-right extremists has been ignored for too long. In Britain the menace is recognised as so serious the security services have taken charge of it. During the Brexit referendum, a campaign swimming in reaction, a Labour MP was shot and stabbed by a neo-Nazi shouting “Britain first”. New Zealand’s prime minister, Jacinda Ardern, has understood the threat the mosque attacks pose to her country’s society, imperilling the values New Zealanders cherish most – their solidarity, their sense of community and their feeling of safety. Many of the victims, she said, may be migrants or refugees and “they are us. The person who has perpetuated this violence against us is not”. Terrorists seek to divide. In grief and anger, communities must stand together.

• 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.