Pope Benedict XVI used his moral authority on Friday to promote human rights and multilateralism and urge a greater dialogue between religions in a landmark address to the UN General Assembly.
Clad in his white robes, the 81-year-old pontiff reminded all 192 UN member states of their duty to protect their people from human rights abuses.
"Every state has the primary duty to protect its own population from grave and sustained violations of human rights," he told a packed assembly on his first visit to UN headquarters since becoming pope three years ago.
"If states are unable to guarantee such protection, the international community must intervene with the juridical means provided in the United Nations Charter," he said.
In his remarks, the head of the world's 1.1 billion Roman Catholics also extolled the virtue of "multilateral consensus" which he said "continues to be in crisis because it is still subordinated to the decisions of a few, whereas the world's problems call for interventions in the form of collective action."
Benedict also underscored the need to foster dialogue between cultures and religions at a time of tension between the West and the Islamic world.
"The United Nations can count on the results of dialogue between religions and can draw fruit from the willingness of believers to place their experiences at the service of the common good," the pope said.
He later entered the sanctuary of the Park East synagogue in New York, becoming the first leader of the Roman Catholic church to visit a Jewish place of worship in the United States.
The visit, by the German-born pope, came just hours before the start of Passover. Benedict walked down the center aisle with Rabbi Arthur Schneier, a survivor of the Holocaust, as a children's choir sang in Hebrew.
"Shalom! It is with joy that I come here just a few hours before the celebration of your Pesah (Passover), to express my respect and esteem for the Jewish community of New York City," Benedict told some 400 people gathered at the synagogue.
It was another sign of the pope's desire for better ties with the Jewish community, after he met privately with Jewish leaders in Washington on Thursday to urge Jews and Roman Catholics to forge "new attitudes" to foster peace.
The six-day ground-breaking trip, Benedict's first as pontiff, has already seen the pope tackle some of the thorniest issues facing the Roman Catholic Church.
His address to the UN was one of the highlights, but on Thursday he took unprecedented steps to atone for decades of sexual abuse of young people by US priests.
After celebrating Mass with some 48,000 people in Washington on Thursday, Benedict met privately with five victims of sexual abuse by priests, acknowledging the pain and damage caused by the scandal.
"I told him that he has a cancer growing in his ministry and needs to do something about it," said 52-year-old Bernie McDaid who was abused as a 12-year-old altar boy near Boston, Massachusetts.
"He absolutely heard it. I felt our eye contact, everything about him. When he entered the room, he had an apology right away," he told CNN.
Noting that this year marks the 60th anniversary of the Universal Declaration of Human Rights, the pope told the UN General Assembly Friday that promoting human rights was "the most effective strategy for eliminating inequalities between countries and social groups and for increasing security."
But he also warned against "a relativistic conception" of such rights under which "the meaning and interpretation of rights could vary and their universality would be denied in the name of difference cultural, political, social and even religious outlooks."
"This great variety of viewpoints must not be allowed to obscure the fact that not only rights are universal, but so too is the human person, the subject of those rights," he added.
His UN visit was the fourth by a pope, following those by Paul VI in 1965 and John Paul II in 1979 and 1995.
The pope's historic visit will continue on Saturday with a Mass at St. Patrick's cathedral followed on Sunday by a visit to Ground Zero, before he celebrates Mass in the Yankees Stadium.
On Wednesday he paid the first papal visit to the White House in three decades and urged US President George W. Bush to use diplomacy rather than war to resolve conflicts.