Last Friday, March 15, hatred struck New Zealand and the entire world.The shooting spree at two Christchurch mosques left people aghast, shocked and asking a slew of questions.New Zealand, like many other countries, is home to citizens with a wide range of ethnic, communal and religious identities who wish to live peacefully alongside each other.But every so often hatred rears its head, and hate crimes take place in Europe, the USA, and now even in far-off New Zealand. These are crimes in which a person or group decides to take the law into their own hands, and carry out a spontaneous or pre-meditated acts aimed at causing as much harm, fright, and damage as they possibly can. Such incidents leave behind destroyed families, bleeding communities, and a sense of fear that undermines the sense of personal safety of most members of the affected community.It is very hard to recover from such an occurrence and restore public confidence in the idea of people of different identities living together in peace.For this reason, these type of crimes are relevant not only to the police, security forces, and political leaders, they are primarily with by communities and their mayors. A city’s mayor has direct and first-hand contact with its residents. He is with them in almost every area of life, and when such terrible acts transpire he cannot sit and do nothing. About one month ago, we – several mayors from around the world – met together and established an international coalition. Our goals were reducing incidents of hatred by education from a young age; taking drastic and significant steps against hatred and racial violence of any kind against any religion or race; and fighting expressions of violence, antisemitism or xenophobia at a municipal level.Together we committed to showing zero tolerance for outbreaks of violence against communities and residents because of their particular ethnic or religious group.The coalition members include Frankfurt am Main Mayor Uwe Becker; Bal Harbour Village Council Mayor Gabriel Groisman; Strasbourg Mayor Roland Ries; and mayors from South America, and Western and Eastern Europe, including Jews, Christians and Muslims. My colleague mayors and I committed ourselves to raising awareness of the need to deal promptly with the problem, and implementing firm measures and punishments against declarations that mention racism and violence. In the same way that Rudy Giuliani proved how graffiti in New York can eventually lead to murder several years later, the desecration of graves in a Jewish cemetery in Strasbourg can end in slaughter and violence against 50 citizens in New Zealand, Las Vegas, Paris, or anywhere else worldwide. I call on all mayors to join our coalition and resolutely demand that lawmakers legislate harsh punishments for revelations of hate by radical parties.Together we can fight them in the streets, educational institutions, social networks and communities to create a better future that is focused on cooperation, mutual respect and unity, and not on hatred and violence.The writer is mayor of Modi’in-Maccabim-Reut, and chairman of the Federation of Local Authorities in Israel, and of the Global Mayors Coalition.