The United Nations rights chief called Monday for the world to learn the hard lessons provided by the Holocaust and reject hatred and dehumanisation "to safeguard our future".
In a statement issued ahead of Holocaust Remembrance Day on Tuesday, Volker Turk insisted that the dark history offered "striking lessons" for the world today.
"It is difficult to fathom that within living memory, a group of deluded killers inflicted unspeakable atrocities on millions of Jews and members of other minorities," he said.
The Nazi regime during World War II "persecuted them, stripped them of dignity, and ultimately murdered them with the horrific efficiency of an assembly line.
"Systematically, openly, and without consequences."
The UN High Commissioner for Human Rights stressed that the "the appalling cruelty was not born in medieval darkness, but in the broad daylight of a supposedly modern society".
"The genocide did not begin with concentration camps and gas chambers; it started with apathy and silence in the face of injustice, and with the corrosive dehumanisation of the other," he said.
"Today, and always, we need to remember this."
Turk highlighted that "in a disturbing trend, threats and assaults against Jews have risen sharply in recent years".
And "hatred and dehumanisation are creeping into our daily lives, including through our social media feeds", he warned.
But Turk stressed there was reason for hope, insisting that people today were "equipped with the memory of how exclusion can turn into annihilation, if we look away".
"We are equipped with education and unprecedented access to information to seek truth and to understand our differences," he said.
"And we are equipped with human rights, backed by international law –- forged from the ashes of war to protect humanity from repeating its darkest chapters."
Turk insisted that "we need to use these tools at all times against the plague of racism, antisemitism, and dehumanisation".
Education about the Holocaust and human rights was vital, he said.
"Above all, we must stand up for our shared humanity – each and every day."