Benedict XVI’s arrival in Washington last night heralds a series of events intended to show solidarity with President Bush at a time of anxiety about Islamic fundamentalism, which threatens both America and the Catholic Church, and the president’s pursuit of the war on terror.

On Sunday, in a display of defiance against Islamic extremism, the pope, who turns 81 today, will commemorate the lives of those who died in the terrorist attacks of September 11, 2001, by kneeling on the bedrock of ground zero and offering a silent prayer to the victims of Islamist terrorism.

Accompanied by Edward Cardinal Egan, he will offer personal condolences to a group of about 20 New Yorkers representing the victims, first responders, and survivors of the attacks.

The Vatican’s ambassador to America, Archbishop Pietro Sambi, said the pope wants to display to the rest of the world his “solidarity with those who have died, with their families, and with all those who wish an end of violence and in the search of peace.” The pontiff intends his visit to signify “a time of spiritual renewal for all Americans.”

While Benedict will meet with Islamic leaders, in particular those who take part in the series of interfaith talks between Muslims and Catholics that began in the early 1990s, some mullahs have chosen to snub him. The pope will not visit a mosque during his six-day visit. He will meet Jewish, Buddhist, Jain, and Hindu leaders tomorrow.

Dismissing the papal visit as “more ceremonial than substantive,” the executive director of the Los Angeles-based Muslim Public Affairs Council, Salam al-Marayati, has declined an invitation to meet Benedict, saying he was disappointed the pontiff did not schedule a special meeting with American Muslim leaders. “It would have been a good opportunity for him to have a dialogue,” he told the Associated Press.

Benedict reached out to leading Muslims after he quoted a Byzantine emperor who linked Islam with violence in a speech at Germany’s Regensburg University in 2006. He set up the Catholic-Muslim Forum that will meet every two years in Rome and in a Muslim country in alternate years, and will attend the inaugural forum in Rome in November.

However, while the pontiff expressed regret if offense was taken by his learned address, he persisted with his exploration of the link between Islam and violence by baptizing in St. Peter’s on Easter Sunday Magdi Allam, an Egyptian-born academic who has condemned the “inherent” violence in Islam.

“Unfortunately, some of the pope’s past statements and actions have led to tensions between Muslims and Catholics,” a co-founder of the Council on American-Islamic Relations, Nihad Awad, wrote in a press release. “It is perhaps best not to dwell on these past events but instead to use them as a springboard to help deepen interfaith dialogue based on mutual understanding and acceptance of differences.”

The pope is also expected to counter a trend that he believes is widespread in America: of “moral relativism” that fails to distinguish between good and evil. On the eve of his election, he declared: “A dictatorship of relativism is taking shape which does not acknowledge anything as definitive and which leaves only one’s own ego and its whims as the ultimate measure.”

He may also allude to his opposition to “liberation theology,” which sees the Catholic Church as a political agent of change, and to the ordination of women.

Benedict, in the first official papal visit since full diplomatic relations between America and the Vatican were established by President Reagan 24 years ago, arrives in New York Friday. (The meeting between Pope John Paul II and President Carter at the White House in 1979 was unofficial.)

He will visit the United Nations, where he will praise the world organization’s Universal Declaration of Human Rights, which declares, “Everyone has the right to freedom of thought, conscience and religion.” Later that day, he will hold an ecumenical mass in St. Joseph Parish, on the Upper East Side.

On Saturday, he will hold a Mass in St. Patrick’s Cathedral before hosting a rally for 25,000 young Catholics at St. Joseph Seminary, in Yonkers. On Sunday, after visiting ground zero, he will celebrate Mass with 60,000 Catholics in Yankee Stadium, when he will meet members of the New York National Guard’s Fighting 69th.