Benedict arrives late Tuesday for a six-day visit to Washington and New York filled with high-profile events. He will meet President Bush at the White House, address leaders in Roman Catholic higher education, speak at the U.N., visit ground zero and hold two stadium Masses before leaving Sunday night.
It will be the first papal visit by Benedict since he was elected in 2005. However, the former Cardinal Joseph Ratzinger -- who will celebrate a birthday and the anniversary of his election to the papacy while in the U.S. -- traveled to America five times during his many years as the Vatican's doctrinal watchdog.
The Rev. David Wells, a theologian at Gordon-Conwell Theological Seminary, a prominent evangelical school outside Boston, met Ratzinger years ago at a conference.
During a coffee break, the Roman Catholic cardinal picked up on a point Wells had made, launching into a detailed discussion of the "Institutes of the Christian Religion," the seminal theological book by John Calvin and a key work on the Reformation.
"I was very impressed by the wide range of his knowledge, his lucidity and the grasp of the issues, both historical and contemporary," Wells said.
Benedict, a former theology professor, has made ecumenical outreach a cornerstone of his papacy, although he has upset some Protestants by affirming that the Catholic Church is the only "true" church. The pope is holding a prayer service with Protestant and Orthodox Christian leaders Friday night at a Manhattan parish.
Ray Flynn, the former Boston mayor who served as U.S. ambassador to the Vatican from 1993 to 1997, recalled Ratzinger walking by a newsstand outside St. Peter's Square where Flynn was looking at papers. Ratzinger stopped and discussed American current events with Flynn for nearly 20 minutes.
"I was just amazed by his level of curiosity and awareness about all that was taking place in the U.S.," Flynn said. "He kept using the phrase, 'the generosity of the United States."'
Flynn is among those hosting a birthday party for Benedict on Wednesday night, his 81st birthday, in Washington. It's not clear whether the pope will attend. The party is among several events related to the visit that aren't on Benedict's official itinerary. He is expected to meet privately with religious representatives and other leaders.
Some Catholics have expressed disappointment that the pope isn't visiting the Archdiocese of Boston. The clergy sex abuse crisis erupted there in 2002 with the case of one predator priest, then spread nationwide and beyond. Abuse-related costs, including massive settlements with victims, have surpassed $2 billion for American dioceses since 1950.
However, Cardinal Tarcisio Bertone -- the Vatican secretary of state -- told The Associated Press that Benedict will address the scandal during his trip and "will try to open the path of healing and reconciliation." A likely forum could be when Benedict speaks to priests during a Saturday morning Mass at St. Patrick's Cathedral in New York.
Archbishop Pietro Sambi, the Vatican's U.S. ambassador, told the National Catholic Reporter that a meeting of the pope and victims is "within the field of possibility."
Karl Anderson, supreme knight of the Knights of Columbus, the Catholic lay fraternal group, said Benedict doesn't get enough credit for his part in instituting reforms in the U.S. church in 2002 and 2003. At the time, he ran the Vatican Congregation for the Doctrine of the Faith, which reviewed all molestation cases against clergy worldwide.
"He was the key person," Anderson said Monday, "in helping the bishops' reforms get through some roadblocks in the Vatican."
Benedict arrives at an uncertain moment in the U.S. church.
With more than 64 million members, it is the largest denomination in the country. However, a recent survey by the Pew Forum on Religion and Public Life found that many U.S.-born Catholics are leaving the church, and that the church is growing mainly because of Hispanic immigration. Liberal and conservative Catholics are still at odds over the modernizing reforms of the Second Vatican Council of the 1960s.
Many Catholic advocacy groups are planning protests around Benedict's visit. On Monday, the Survivors Network of those Abused by Priests asked the U.N. to investigate whether the Vatican's response to abuse violated U.N. protections for children.
The Rev. Joseph Fessio, a former student of Benedict's and founder of Ignatius Press, the pope's English-language publisher, predicted that the pope's visit would draw attention away from what he called the "dimples and dark spots" in the church.
"He has so much interiorized knowledge and love. He's such a deeply cultured and intelligent person," Fessio said. "When someone like John Paul the Second or Benedict comes as a public figure and speaks, there's an integrity that's really clear to anyone with an open heart and open mind."