COLOGNE, Germany - Pope Benedict, making a historic visit on Friday to a synagogue once destroyed by the Nazis, said Christians and Jews must join forces so the "insane racist ideology" that led to the Holocaust never resurfaces.
A Jewish leader called on him to open up all the Vatican's archives dealing with World War 2 and the Holocaust -- a sore point between some Jews and the Holy See.
The Pope, who served briefly in the Hitler Youth during the war when membership of the Nazi paramilitary organisation was compulsory, paused to pray at a memorial to the six million killed as he began the landmark visit.
The atmosphere was thick with significance and history -- a German Pope listening as Rabbi Netanel Teitelbaum intoned the Kaddish, the Jewish prayer for the dead, and the sound of the blowing of the Schofar, a ram's horn, filled the temple.
Benedict, who began his speech with the Hebrew words "Shalom lechem (peace unto you)" became only the second Pope known to have visited a synagogue since the early days of the Church some 2000 years ago. John Paul visited a Rome synagogue in 1986.
Speaking in the temple destroyed in the anti-Jewish Kristallnacht attacks in 1938 and rebuilt in 1959, he called the Holocaust "this unspeakable and previously unimaginable crime".
"In the 20th century, in the darkest period of German and European history, an insane racist ideology, born of neo-paganism, gave rise to the attempt, planned and systematically carried out by the regime, to exterminate European Jewry," he said.
While Catholic-Jewish relations have improved tremendously in the past half-century, particularly during the 27-year pontificate of John Paul, Benedict warned that new threats of racism and anti-Semitism were always lurking:
"It is a particularly important task, since today, sadly, we are witnessing the rise of new signs of anti-Semitism and various forms of a general hostility towards foreigners."
"How can we fail to see in this a reason for concern and vigilance? The Catholic Church is committed -- I reaffirm this again today -- to tolerance, respect, friendship and peace between all peoples, cultures and religions," he said.
He repeated a promise he has made to Jews since the start of his pontificate that he would "continue on the path towards improved relations and friendship" blazed by John Paul.
"Yet still much remains to be done. We must come to know and love one another much more and much better," he said.
In his address to the Pope, one of the Jewish community's leaders, Abraham Lehrer, urged the Pope to open the Vatican's historical archives for the wartime period.
Some Jews say a total opening of he archives would help scholars shed light on the controversy surrounding the role of wartime Pope Pius XII.
Many Jews say Pius, Pope from 1939 to 1958, turned a deaf ear to the Holocaust. The Vatican says he worked behind the scenes to save Jews and did not speak out more forcefully for fear of instigating Nazi reprisals.
"You grew up in Germany during a terrible time," Lehrer told Benedict. "We not only see in you the head of the Catholic Church but also a German who is aware of his historical responsibility."
Lehrer's elderly mother was in the audience and Rabbi Teitelbaum told the Pope her story:
"On her lower arm you can see the number with which she was tattooed in the concentration camp. In 1944 in Auschwitz she had neither the strength nor the power of imagination to think that one day in 2005 her son would officially greet the Pope in Cologne synagogue."
Later on Friday, Benedict met Germany's Protestant leaders. He told them he knew many Christians were hopeful of closer ties, and the divisions between them were against God's will.
The head of Germany's Protestant Church Council, Bishop Wolfgang Huber said after the meeting: "I leave these talks encouraged and confident that we can make a big contribution to ecumenism in Germany."
- REUTERSBy Tom Heneghan, Philip Pullella