Pope Francis, now on his historic first visit to the United States, is encountering a Catholic population that is part of a universal church with very American challenges.
From the devout grandma in a lacey veil who never misses Mass, to the young gay man who struggles with church teaching on homosexuality, American Catholics are about as diverse as the country itself, said Mary Ellen Konieczny, a sociology professor at the University of Notre Dame in Indiana.
This population can be sharply divided on social issues. The majority of Catholics reject the church's traditional stances on sex, marriage and family life, while that orthodoxy is a draw for a small but vibrant group of young traditionalists. But from conservative to liberal to somewhere in between, many practicing Catholics say the hot-button issues are a small part of their experience in the U.S. church. [Infographic: Views of Catholics in America by the Numbers]
"When Pope Francis speaks out on social justice, the 'conservatives' run away, and when Pope Francis talks about pro-life issues, the 'liberals' run away," said Edward Alonzo, a Web designer and former lay minister with the church in San Antonio. "The Catholic Church isn't about a political system. It's about a consistent ethic and belief."
And though the church can sometimes seem unusually fractured to outsiders, debate and disagreement are actually long-standing traditions in Catholicism, Konieczny said.
"Catholicism has always tolerated diversity in its practice," Konieczny told Live Science. "The church is a big tent."
Disconnect and exclusion
The U.S. Catholic population is largely at odds with the church on social issues such as same-sex marriage, cohabitation, contraception, abortion, and divorce and remarriage. The Catholic Church views all these practices as immoral (some gravely so), while most parishioners do not.
This disconnect can cause struggles for people in the pews.
The challenge for American Catholics is "how do you deal with those things that seem to be antiquated, that seem to be based on rules that were in place many, many hundreds of years ago?" said Claudio Bauza, a consultant for the food industry in Atlanta, who is also a catechist (Sunday school teacher) for the church.
For Bauza, one of the biggest sources of struggle is the church's treatment of divorced and remarried Catholics.
Church teaching holds that marriage was created by God as a permanent institution, specifically for the good of partners and the children they may have. In this view, Catholics who were truly married in God's eyes can never be divorced.
Follow the logic, and that means Catholics who do not have their first marriages annulled by the church (meaning the marriages never really happened in God's eyes) are therefore living in sin or perpetually committing adultery. Because people in a state of mortal sin cannot take communion, divorced and remarried parishioners are not supposed to participatein the Mass, the central rite of the church.
Yet that state of affairs feels unjust to Bauza, he said. A murderer who says he has repented can still take communion, whereas a divorced and happily remarried man cannot, Bauza said.
"It's a personal issue with me because I am divorced, and I still feel very close to the church and to its people," Bauza told Live Science. "I have the same level of involvement that I had before, so why should something like that make me a second-class Catholic?"
Gender and sexuality
Becky Schwantes-An, a board member for the Vision Council, the largest progressive Catholic organization, sees huge sticking points in the church's stance on gay, lesbian and transgender rights; contraception; and the prohibition on the ordination of women.
The church holds that one of the primary purposes of sex is procreation, so contraception is immoral because it is a deliberate attempt to sever the connection between sex and babies. Same-sex marriage is not considered a true marriage in the church's eyes, because intercourse between two people of the same sex can't produce children.
As for the ordination of women, the church sees male priests as literally taking on the persona of Christ (called the Alter Christus) during the celebration of Mass. Since Jesus was male, as were all of his apostles, women cannot take on the Alter Christus and become priests, the church argues.
That doctrine feels incredibly alienating, Schwantes-An said.
"I do believe in the ordination of women and feel called to that myself," Schwantes-An told Live Science. "To be denied that in my faith is very challenging and hurtful."
Small but vibrant group
While many in the pews either ignore or struggle with church teachings, a small but vibrant group of younger folks not only accepts Catholic doctrine on controversial issues, but also sees it as beautiful. [The Most Fascinating Catholic Saints]
For instance, Alonzo started out as an atheist and was originally ambivalent about abortion. (Disclosure: Alonzo is a friend of the reporter's.)
After a conversion experience, "I submitted my will to God and said, 'I'll let you explain it to me, and while you're explaining it to me and changing my heart, I'll try to act on what I understand to be your teachings,'" Alonzo told Live Science.
Now, he views the church's teachings on abortion, sexuality and marriage as logical, consistent and beautiful, because they honor the "dignity of the human person," he said.
Fewer members of the millennial generation identify as Catholic compared to previous generations. That may be because "to really be able to call themselves Catholic, they feel they have to agree with everything the church teaches," whereas past generations may have been more comfortable disagreeing with church's stances while holding onto the Catholic identity, Konieczny speculated.
But as Konieczny observed, this change has meant those who do identify proudly as Catholic tend to be more devout. They tend to engage in more devotional practices such as reciting the rosary and attending Eucharistic adoration (in which people can sit quietly in a chapel where communion wafers, which are considered the body and blood of Christ, are on display), she said. Millennials who are considering becoming nuns or sisters also tend to be drawn to orders with more traditional practices, such as contemplative prayer and the wearing of habits, Konieczny added.
More important facets of faith
Even for those struggling with the church, the most divisive issues represent a very small part of church teaching or their experience of what it means to be Catholic.
"You can wrestle with those issues and still be strong in your faith," said Matt Gronski a social worker living in Lake St. Louis, Missouri. [Religious Mysteries: 8 Alleged Relics of Jesus]
For Gronski, the most meaningful experiences are encountered during the rituals, including the Eucharist, which Catholics believe actually becomes the body and blood of Jesus.
"One of the beauties of the church is the tradition, the routines," Gronski told Live Science. "When you really dig deep, they're very beautiful. There's a lot of deep meaning behind them."
That tradition was part of why Schwantes-An chose to get her young son baptized in the Catholic Church, she said.
"The ritual and the tradition is very rich, and it's very nourishing, and that's why we've continued [to remain in the church]," Schwantes-An said.
For Ellen Finnigan, a cradle Catholic living in Estes Park, Colorado, the 2,000-year-old intellectual tradition is a big draw. (Cradle Catholics are people who have been raised in the church since birth.)
"Obviously the relationship with Christ is very important, but just for me personally, it's helpful to have that scholarly tradition as well to underpin that," Finnigan told Live Science. "That's probably one of the reasons why I've stayed Catholic as I've gotten older."
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Tia is the managing editor and was previously a senior writer for Live Science. Her work has appeared in Scientific American, Wired.com and other outlets. She holds a master's degree in bioengineering from the University of Washington, a graduate certificate in science writing from UC Santa Cruz and a bachelor's degree in mechanical engineering from the University of Texas at Austin. Tia was part of a team at the Milwaukee Journal Sentinel that published the Empty Cradles series on preterm births, which won multiple awards, including the 2012 Casey Medal for Meritorious Journalism.