Pope Benedict XVI on Friday paid only the second visit to a synagogue by a Roman Catholic pontiff, decrying "the insane, racist ideology" practiced by his fellow Germans that led to the Holocaust and World War II.

Benedict, a conscripted teenage member of the Hitler Youth who was forced to join the German military during the waning days of the war, memorialized the 6 million Jews who died in the Holocaust, visiting a synagogue that was destroyed in 1938 on the night of Nazi-fomented violence known as Kristallnacht. It was finally rebuilt two decades later.

"The holiness of God was no longer recognized, and consequently contempt was shown for the sacredness of human life," Benedict said. He quoted his predecessor, John Paul II, who said memories of the Holocaust must "never cease to rouse consciences, to resolve conflicts, to inspire the building of peace."

Catholic and Jewish leaders described Benedict's visit to the Cologne synagogue as an important milestone in relations between their two religions, which improved considerably during John Paul's 27-year reign but suffered some setbacks in recent months. They said the mere presence of a German pope -- the first in 500 years -- in a synagogue was something they could not have imagined until recently.

"This was an event that not only has exceptional meaning for Germany, not only for the Catholic Church, but also for the Jewish community in Germany and in the world," said Paul Spiegel, director of the Central Council of Jews in Germany . "It is a historic day, an event that will be thankfully remembered by future generations."

Upon entering the Jewish house of worship, Benedict stopped to pray briefly at a memorial to Jews who died in the Holocaust, including about 11,000 from Cologne, which served as an important European center of Jewish learning and culture from the 4th century until the Nazis decimated the community.

Benedict, 78, whose trip to Germany is his first foreign mission since becoming pope in April, began his speech inside the synagogue with a few words in Hebrew, saying "peace unto you." The only other pope known to have entered a synagogue in modern times was John Paul II, who visited one in Rome in 1986 and also made a historic visit to Jerusalem.

While Benedict spoke of the common theological ground between the Jewish and Catholic faiths, he did not apologize for the church's failure to take a stronger public stand against the Nazis during World War II and the Holocaust, as many Jewish leaders have urged the Vatican to do.

Abraham Lehrer, a Jewish community leader in Cologne, asked Benedict during the synagogue visit to open more of the Vatican's World War II archives to researchers studying the church's response to the Holocaust. Such a gesture "would be a further sign of historical conscience and would also satisfy critics," Lehrer said during the ceremony.

Benedict did not respond directly. But he made a general reference to such disputes, saying he "would encourage sincere and trustful dialogue between Jews and Christians, for only in this way will it be possible to arrive at a shared interpretation of disputed historical questions."

Many Jewish leaders, including several in Germany, praised Benedict's election as pope in April, saying he shared John Paul's commitment to mending relations between Jews and Catholics. But the new pope has had to deal with some controversies in the past year.

Benedict drew criticism from the Israeli government last month after he failed to include Israel among countries hit by terrorism in a statement decrying the London suicide bombings and other recent attacks. The Vatican responded with criticism of its own, accusing Israel of trying to tell the pope what to say.

In January, Cardinal Joachim Meisner, the archbishop of Cologne, a close ally of Benedict's, gave an address in which he equated the casualties of the Holocaust with abortion and euthanasia. Meisner apologized a few days later after Jewish leaders in Germany and elsewhere condemned his remarks.

Vatican officials portrayed the synagogue visit on Friday as Benedict's idea. Joaquin Navarro-Valls, the papal spokesman, said it was "an event of historic significance" and emphasized that the pope "himself took the initiative and said he wanted to visit the synagogue."

Lehrer said, however, that the Jewish community board of directors in Cologne had taken the first step. He said the board decided shortly after John Paul's death in April to send a congratulatory letter and invitation to whomever would be named his successor, realizing that the new pope was likely to visit Cologne this month to attend a previously scheduled Catholic world youth summit.

"We decided, well, we're going to invite whoever the winner is and we'll see what will happen," Lehrer said. He said the Vatican responded eagerly soon after Benedict's election, formally accepting the invitation in June.

"He grew up in Germany and is what we Germans call a child of the war," Lehrer said. "This makes it much easier for him to understand the special feelings of the Jews in Germany and to accept an invitation to visit our synagogue in Cologne."

Benedict was scheduled to continue his outreach to leaders of other faiths on Saturday in a meeting with Muslim leaders in Cologne.

Special correspondent Shannon Smiley contributed to this report.

Benedict XVI, right, takes a shofar -- a ram's horn blown on holy days -- from worshipers at a synagogue in Cologne.