The plight of Christians and other Middle East minorities demands action from the international community, one leader in relief efforts said in a panel at the United Nations.

“We have a unique opportunity to change things for the better,” said Carl Anderson, head of the Knights of Columbus. “Never before has the world’s attention been so focused on the suffering of these minorities. Never has their plight been so high on the agenda of the world’s governments, the vast majority of the world’s Muslims, and all people of good will.”

He said the Middle East crisis is “the world’s greatest humanitarian crisis since World War II.”

He cited hundreds of thousands of deaths in Syria and Iraq, the displacement or extermination of entire communities, and the strain of millions of refugees from war and terrorism.

“We face the very real prospect of the extinction of many of the communities indigenous to the region,” Anderson said at a Thursday panel at the United Nations’ Economic and Social Council Chamber.

The panel was sponsored by the Holy See’s permanent observer mission to the U.N. The event was part of the #WeAreN2016 congress, being held at various New York City venues from April 28-30. The congress’ name derives from the Arabic letter “nun” that was painted on the homes of Christians targeted for persecution by Islamic State group sympathizers. Some supporters of these Christians have adopted the symbol as a sign of solidarity.

The Knights of Columbus is a Catholic fraternal organization with over 1.8 million members worldwide. The organization has raised more than $10.5 million for relief for Christians and other displaced persons and refugees in Iraq, Syria, Jordan and Lebanon.

It has also advocated official U.S. government recognition of violence against Christians and other minorities as genocide. Anderson said the Knights’ 300-page report documented atrocities and made the legal arguments in favor of such recognition.

“ISIS and the victims we interviewed agree on one thing. Many of those targeted were targeted because of their Christian faith,” he said.

He cited a fact-finding mission that found evidence of widespread rape, kidnappings, forced conversions, slavery, murder and forced expulsion.

“Many of the incidents had not been previously reported. But based on what we learned, it is our impression that what we know today is likely to be only the tip of the iceberg,” Anderson said. “A concerted, sustained effort now needs to be undertaken to document the extent of this tragedy.”

He said those interviewed showed “great heroism.” These included people like Kahlia, a woman in her fifties. She was held hostage with 47 other people in Iraq. During her 15-day captivity, she resisted demands to convert to Islam even at gunpoint or when a sword was held to her neck. She physically resisted Islamic State group militants who tried to rape hostage girls or take them as brides.

“Although 14 men in the group were coerced into saying they would convert to Islam, Kahlia did not. She told her captors that since Jesus died for her, she could die for him,” Anderson said.

She was not killed, but left in the desert to walk to Erbil. Her resistance saved many people, refugees reported.

“We know that ISIS has killed thousands of Christians in Iraq, Syria, and Libya,” Anderson continued. “Mass graves have been reported in Syria, and the desert between Mosul and Erbil was littered with bodies as Christians there fled too quickly to bury neighbors and family members.”

He said Christians in Iraq numbered 1.5 million in early 2000s, and now are as few as 200,000 due to war and immigration. The Christian population in Syria has fallen from 1.5 million to 500,000. Indigenous Christian communities are “vulnerable and fragile” and at risk of disappearing entirely.

“The world stands at a crossroads. The rich tapestry of religious pluralism in the region must be preserved now or it will be lost forever,” Anderson said. “If Christianity disappears in this region, so does the opportunity for pluralism there; and the likelihood of majoritarian theocracy, or something worse, is increased. The threats from such an outcome to peace, stability and security — in the region and beyond — are substantial.”

He recommended four forms of action for the United Nations.

These include Security Council referral of perpetrators of genocide to the International Criminal Court; provision for locating and providing relief for Yazidis, Christians and other minorities targeted for genocide; advocacy for full rights for religious minorities; and preparation for the liberation of Islamic State group-controlled territory and restoration of the property of attempted genocide victims.

He noted that many refugees fear going into official U.N. refugee camps. They are overlooked and face difficulty in acquiring official refugee status or in emigrating.

“If displaced persons want to return home, they should be supported — legally and actually — in that choice,” Anderson said. “For those who have suffered too much to return to their homes—refugees who have decided to remain in the places to which they fled, they should be allowed to do so. “The support of the international community will be critical on both counts.”