Pope Benedict XVI prayed at Auschwitz Sunday and denounced the mass murder of Europe's Jews by his native land's World War II rulers, saying it was hard for "a pope from Germany" even to speak of the Holocaust. "To speak in this place of horror, in this place where unprecedented mass crimes were committed against God and man, is almost impossible - and it is particularly difficult and troubling for a Christian, for a pope from Germany," the 79-year-old pontiff said. "In a place like this, words fail; in the end, there can be only a dread silence, a silence which itself is a heartfelt cry to God: Why, Lord, did you remain silent?" Benedict walked along the row of plaques at the Auschwitz-Birkenau complex's memorial, one in the language of each nationality whose members died there. As he stopped to pray, a light rain stopped and a brilliant rainbow suddenly appeared over the camp. During his remarks, Benedict said that just as his predecessor, John Paul II, had visited "this dreadful place" as a Pole in 1979, he came as "a son of the German people." He mostly avoided his native language, however, speaking in Italian and using German for just one short prayer. "The rulers of the Third Reich wanted to crush the entire Jewish people, to cancel it from the register of the peoples of the earth," he said, standing near the demolished crematoriums where the Nazis burned the bodies of their victims. "By destroying Israel with the Shoah, they ultimately wanted to tear up the taproot of the Christian faith and to replace it with a faith of their own invention." Benedict's visit, shortly before he was to take off for Rome from nearby Krakow, was a somber close to a four-day trip that was otherwise upbeat, with some 900,000 people turning out for his Sunday mass in a meadow in Krakow, the town where John Paul II once served as archbishop. It's the third time Benedict has visited Auschwitz and the neighboring camp at Birkenau; the first was in 1979, when he accompanied John Paul, and in 1980, when he came with a group of German bishops while he was archbishop of Munich. Benedict arrived first at the Auschwitz part of the complex, walking solemnly with hands clasped through the gate with its infamous words, "Arbeit Macht Frei" or "Work Sets You Free." He prayed at the Wall of Death, where the Nazis executed thousands, and met 32 camp survivors, most of them Catholics. The sometimes-reserved Benedict stopped to speak to each one, clasping one woman's face in his hands, and kissing the cheeks of one of the men, Henryk Mandelbaum, the only Jewish survivor in the group. Benedict did not refer to collective guilt by the German people, but instead focused on the Nazi rulers. He said he was "a son of that people over which a ring of criminals rose to power by false promises of future greatness... our people was used and abused." Rabbi Marvin Hier, founder and dean of the Los Angeles-based Simon Wiesenthal Center, told AP that Benedict's presence at the camp, and his remarks, were firm reminders that Holocaust deniers were not speaking the truth. "He wore the uniform of the Hitler Youth. For him to now go there as the pope and acknowledge the horrors the holocaust visited on the Jewish people and all mankind is important," he said. Poland's chief rabbi, Michael Schudrich, who said kaddish during the ceremony, said the most important part of Benedict's message "was his physical presence at Auschwitz" but that some Jews wished he had gone further by directly addressing anti-Semitism. "It was a very powerful statement and the words that we heard were powerful, but I'm sure some felt a glaring omission... on the question of anti-Semitism. Jews are very sensitive to that and we are used to hearing the words of John Paul II." Schudrich himself was punched and sprayed with what appeared to be pepper spray by an unidentified man in downtown Warsaw, but escaped without injuries from what police said may have been an anti-Semitic attack. Prime Minister Kazimierz Marcinkiewicz called Schudrich to express his regrets and "declare that there is no place for anti-Semitism," government spokesman Konrad Ciesiolkiewicz told the news agency PAP. The US ambassador to Poland, Victor Ashe, visited Schudrich on Sunday to express his sympathy and solidarity. The Conference of European Rabbis, meanwhile, strongly condemned the attack on Schudrich. "We have to recognize that violent manifestations of anti-Semitism always follow an acceptance of anti-Semitic discourse within the public sphere," said CER executive director Rabbi Aba Dunner. "The recent entrance of ministers with a background of anti-Semitic discourse into the new Polish government should be a warning sign to all of us."