VATICAN CITY – Charting a papacy in the tradition of his predecessor, Pope Benedict XVI pledged yesterday to work for unity among Christians and to seek “an open and sincere dialogue” with other faiths.

In his first Mass as pontiff, Benedict invoked the words of John Paul II – “Be not afraid” – a message designed to show he is intent on following the groundbreaking path of the late pope.

The German-born pontiff also stressed he would draw on the work of the Second Vatican Council, the 1962-65 meeting that modernized the church, an issue important to liberals who are wary of Benedict from his time as Roman Catholicism’s doctrinal enforcer.

As the world’s 1.1 billion Catholics got the first hints of where the papacy is headed, followers of other religions weighed its meaning for interfaith relations. By and large, reactions were hopeful and expectant.

“I think he has been very open, so I have no worries about the ecumenical route,” said British Cardinal Cormac Murphy-O’Connor. “It will continue. No doubt at all.”

Benedict, the former Cardinal Joseph Ratzinger, said his primary task would be to try to reunify all Christians and stressed that sentiment alone was not enough. “Concrete acts that enter souls and move consciences are needed,” he said.

The 78-year-old pontiff said he wanted to continue “an open and sincere dialogue” with other religions and would do everything in his power to improve the ecumenical cause.

But Benedict has been one of the most forceful Vatican voices for Catholic missionary work and other forms of evangelization. He was the intellectual drive behind the 2000 document “Dominus Iesus,” which outlined the Catholic Church as an exclusive road to salvation and angered Protestants, Jews, Muslims, and other non-Christians.

In Israel, admiration for John Paul’s tireless efforts to promote Jewish-Catholic reconciliation mixed with unease about Benedict’s time in the Hitler Youth as a teenager.

Benedict has written about his service, which was compulsory under the Nazi regime. He also was drafted into a German anti-aircraft unit at the end of World War II, though he says he never fired a shot.

John Paul won many Israeli hearts during a trip to the Holy Land in 2000 by apologizing for Roman Catholic wrongdoing, over the centuries. He also was praised for promoting interfaith dialogue, establishing diplomatic relations with Israel, and aiding Polish Jews during the Nazi era.

“Israel can certainly coexist with him,” Oded Ben-Hor, Israel’s ambassador to the Vatican, said of the new pope. “But the real test will come over the course of time.”

Benedict inherits sometimes testy relations with the Russian Orthodox Church, which has accused Catholics of poaching Orthodox believers. John Paul, the first Slavic pope, saw a visit to Russia as a way to promote greater Christian unity a millennium after the east-west schism, but he was not able to arrange the trip.

“We very much hope that, under the new pope, those problems will be solved,” an Orthodox church spokesman, Igor Vyzhanov, said.

But Russian religion expert Alexander Ogorodnikov questioned whether Benedict will match John Paul’s zeal for closer ties. As a cardinal, the new pope soured relations with the Russian Patriarchate by backing a move to stop referring to the Orthodox branch of Christianity as a “sister church” – since Roman Catholics see Rome as the “mother” church.

“There may even be a certain cooling of relations,” Mr. Ogorodnikov said.

Benedict’s election Tuesday was welcomed across the Islamic world, where many people hope he will promote harmony between the two religions and possibly Middle East peace. The new pope has supported the Vatican’s cautious overtures to mainstream Islamic leaders, but has been critical of perceived discrimination of Christians and Christian institutions in Muslim regions, including parts of the Holy Land.

In an interview in 2003 with the Italian newspaper Il Giornale, Benedict urged Islamic leaders and politicians to seek policies that “create a space for freedom” for all faiths.

And he won praise from Muslims by criticizing Italian Prime Minister Berlusconi for comments in 2001 that Western civilization is superior to Islam. “One cannot speak of the superiority of one culture over another, because history has shown that a society can change from one age to another,” he said at the time.

However, Benedict has objected to the bid by mostly Muslim Turkey to join the European Union, which he feels would be incompatible to the continent’s Christian history and traditions.

Benedict’s predecessor was warmly regarded by Muslims. John Paul was the first pope to visit a mosque, urged religious tolerance, spoke out against the American-led war in Iraq, and called for a peaceful end to the Arab-Israeli conflict.

“The late pope took brilliant and daring stands, and we hope the new pope would follow his example,” a prominent Syrian cleric who accompanied John Paul on his historic visit to Damascus’s Omayyad Mosque in 2001, Sheik Salah Keftaro, said.

But in India, a leading Hindu organization accused Benedict of religious intolerance because he helped draft “Dominus Iesus.”

“Such a mind-set that ‘we are superior to others’ leads to conflict,” K.S. Sudarshan, head of Rashtriya Swayamsevak Sangh, the parent body of most Hindu nationalist groups in India, said.

Given John Paul’s tireless traveling to promote both Catholicism and interfaith dialogue, Benedict’s impact will depend on his health, vigor, and the ability of a relatively shy man to captivate crowds.

The new pope himself predicted a “short reign” in comments to cardinals just after his election, and his brother said yesterday he worried about the stresses of the job on a man who just turned 78.

While there are no indications that Benedict suffers from any serious or chronic medical problems, there have been ailments in the past – including a 1991 hemorrhagic stroke – that raise questions about how long his papacy will last.

The Vatican refused to comment yesterday on Benedict’s health.

Several cardinals, however, agreed yesterday that Benedict’s term will be marked in years, not decades, and that it was unlikely the pope will match the globe-trotting pursued by John Paul II.

“We’ll see what he feels like. I mean, he’s not a 56-year-old, you know,” said Cardinal Murphy-O’Connor. “He’s a little bit older than that. So he may not do too much traveling. But you never know.”

Benedict has promised to attend World Youth Day in August at Cologne, Germany, which should be a crucial homecoming. It will also be a test of whether he can overcome his reserved, intellectual persona.

“He’ll need to learn a new style,” American Cardinal Avery Dulles told the Associated Press. “He’s the type of person who thinks three times before he says something.”

But the idea that the 115-man College of Cardinals chose Benedict because they wanted a “transitional pope” is wrong, Polish Cardinal Zenon Grocholewski said in an AP interview.

“Absolutely not,” he said. “I think the thought was to find a strong figure, clear – clear identity for the Catholic Church as it faces the world.”

Hundreds of people clapped and cheered yesterday evening as the new pope rode by in a black Mercedes on the short trip to the Vatican from his longtime apartment just outside the city-state’s wall.

Earlier, Benedict broke the seals of the papal apartment – shuttered after John Paul died April 2 – and greeted colleagues then signed papers at his desk. However, he decided to stay for now at the Vatican hotel where he has been sequestered since the conclave began, Vatican spokesman Joaquin Navarro-Valls said.

During lunch yesterday with colleagues, Benedict also outlined his activities over the next few days: a meeting with cardinals Friday, a news conference Saturday, his inauguration service Sunday, and an audience with official delegations Monday, Mr. Navarro-Valls said.

After Benedict’s election, German Cardinal Joachim Meisner said the new pontiff looked “a little forlorn” when he went to change into his papal vestments.

But later, the reputedly frugal pope asked cardinals to dine together on bean soup, cold cuts, a salad, and fruit, Cardinal Meisner said. There were two special treats: ice cream and champagne.