Catholic colleges and universities are trying to balance their religious identity with free expression, catching grief from liberals and conservatives in the process.
Immigrants are filling the pews, while whites are leaving them. Nearly one-third of U.S. adult Catholics are now Hispanic, and they worry about being considered a separate, ethnic church.
Despite these divisions, Catholics across the spectrum of belief have been energized by the pope's trip. The man who was once responsible for enforcing adherence to Catholic doctrine isn't likely to do much scolding. Instead, he's expected to recognize the relative vibrance of the American church, while emphasizing core Catholic values: the reality of absolute truth, the relationship between faith and reason, love for the faith.
"I think he's going to come in and try to inspire. As pope, he's really taken the positive track on a lot of issues. I don't think there's any reason he wouldn't continue to do so now," said Dennis Doyle, a theologian at the University of Dayton, a Marianist school in Ohio.
Benedict has traveled to seven other countries since he was elected in 2005, but a papal journey to the U.S. is like no other because of the church's size and influence.
In a nation founded by Protestants, Catholics comprise nearly one-quarter of the population. Catholic America is the biggest donor to the Vatican. The U.S. also is home to more than 250 Catholic colleges and universities.
There's an added urgency to this visit. While it will be Benedict's first trip to the country as pope - he made five visits when he was Cardinal Joseph Ratzinger - it may also be his last. He turns 81 during his April 15-20 visit to Washington and New York, and he has less interest in travel than his globe-trotting predecessor, Pope John Paul II.
Americans don't know much about Benedict. But surveys conducted ahead of his visit found three-quarters of U.S. Catholics view him favorably. They are clamoring to see him.
"I get 30 to 40 requests a day to get into the speech he's going to give at Catholic University," said the Rev. David O'Connell, president of Catholic University of America, where Benedict will address leaders of the nation's Catholic colleges and universities. "There's a fascination with Pope Benedict, perhaps it is because there is more mystery about him."
They have less enthusiasm for religious observance.
About one-third of the more than 64 million U.S. Catholics never attend Mass, and about one-quarter attend only a few times a year, according to a 2007 study by the Center for Research in the Apostolate at Georgetown University. A majority never go to confession or go less than once a year.
The generational split is stark: About half of Catholics born before the 1960s say they attend Mass at least once a week, compared to only 10 percent of those born since the 1980s.
One of Benedicts' core goals is strengthening Catholic culture to combat these trends, stressing the importance of religious life, and observing Holy Communion and other sacraments.
Beyond religious practice, young and old American parishioners hold vastly different worldviews.
Older Catholics who remember the Second Vatican Council of the 1960s are still debating its modernizing reforms. The council changed everything from the role of lay people to the direction priests face while celebrating Mass.
Benedict has revived some traditions and prayers that had been largely abandoned since Vatican II, refueling the debate.
But young adult Catholics are fed up with the fight, according to James Davidson, a Purdue University sociologist of religion who studies American Catholics.
"They've become very impatient, and probably rightly so, with older generations, who see everything in terms of conservative-liberal, liberal-conservative, who they see as sometimes enjoying the ideological battle, even if it doesn't get them anywhere," Davidson said. "Problems aren't being solved, but people are yelling at one another."
The next generation of priests generally hold that same outlook.
Monsignor Thomas Nydegger, vice rector of the Immaculate Conception Seminary School of Theology at Seton Hall University, said seminarians today are reaching back in Catholic tradition - like Benedict does - for rituals and clerical garb they find inspiring.
But they blend that interest with modern church goals: to serve parishioners and the larger community and to reach out to people of other faiths, he said.
"There is a great sense of the pastoral needs of the people of our parishes - the sick, the dying, the people dealing with tragedies in their lives," Nydegger said. "They want to reach out and let them see that the church embraces them."
Unfortunately, their numbers don't match their zeal.
The priesthood has been shrinking for decades. More than 3,200 of the 18,600 U.S. parishes don't have resident priests. Some dioceses are now hiring recruiters to travel overseas to find clergy candidates. The number of priests from other countries is growing so steadily that Seton Hall and other seminaries have been adding English classes, hiring accent reduction tutors and developing courses explaining U.S. culture - inside and outside the church.
After ordination, the men are finding fewer resources to support their work.
While U.S. Catholics donate the most to the Vatican of any country, they donate to the local church at about half the rate of Protestants, according to Chuck Zech, a Villanova University professor who studies church finances. Church buildings are aging and are badly in need of maintenance. As the Catholic population grows in the South and West, new parishes are needed.
Many dioceses still haven't adjusted to the loss of free labor from nuns and priests, and are paying such low wages that turnover in schools and for other church work is high, Zech said. The Lay Faculty Association, a teachers' union, recently authorized a strike at 10 New York-area Catholic schools during Benedict's visit.
Beyond the daily expenses, dioceses have been paying out hundreds of millions of dollars in claims since the clerical sex abuse crisis erupted in 2002. Abuse-related costs for the church since 1950 have surpassed $2 billion.
One visit from Benedict won't solve the problems of the American church. But by coming to the U.S., he can show Catholics - even briefly - what it might be like to be truly united by faith.