At a U.N. ceremony on Wednesday marking International Holocaust Remembrance Day, President Reuven Rivlin urged the world's nations to fight genocide saying "the Holocaust of the Jews was not the final chapter in the brutal scheme of man against his fellow man." He cut his visit to the United States short, flying to Israel on Thursday, due to the Hezbollah attack that killed two soldiers and wounded seven others. "I stand before you at a time of great tension in our region," he said at the U.N. ceremony. "My heart and my thoughts are with my people in Israel. Terrorism does not distinguish between blood. In this war, all of us, all the nations united, countries of the free world, must form a united front, Rivlin told the U.N. commemoration of the 70th anniversary of the liberation of the Auschwitz concentration camp that evil is not limited to any religion, country or ethnic group and warned that it is wrong and misleading to view Islam, Judaism, or Christianity, as "enemies of the world." He cautioned against attributing fundamentalism to a particular religion. He criticized the United Nations, which was founded on the ashes of World War II with a mission to prevent genocide, for failing to end the slaughters carried out in Bosnia, Rwanda, Sudan, Cambodia, Syria, Nigeria and elsewhere. Rivlin urged the 193 U.N. member states to set "red lines" that define genocide -- "and to agree that the crossing of those red lines makes it compulsory to intervene." He told the audience that the slogan "never again" is not just a pledge by the survivors, and also not a pledge by the world only to the members of the Jewish People. 'Never again' is, first and foremost, the very essence of this United Nations Organization, it is its mission, it is the primary and principal rationale for its existence." Holocaust survivor Jona Laks movingly described how she was taken from the Jewish ghetto in Lodz, Poland to Auschwitz and marched before feared Nazi Dr. Josef Mengele who sent her on the line to the crematorium and her twin sister on the line for work. "I was already able to see the smoke coming out," she said, when their older sister told Mengele that she was a twin. Laks said that's how she was saved, but she and her twin sister, along with hundreds of other twins, became subjects for horrific experiments conducted by Mengele, who was known as the "Angel of Death." Laks, who is about 85 and lives in Tel Aviv, said she still suffers "immeasurable pain." The Holocaust "symbolizes the failure of 2,000 years of Western civilization," she said. "The message is not to forget -- and also that human life is sacred. We should do everything to preserve it." The Auschwitz anniversary was on Tuesday but the commemoration was held Wednesday because a snow storm shut down much of New York City.