In this photo provided by the Vatican paper L'Osservatore Romano, Pope Francis speaks at the World Meeting of Families on Monday at the Vatican. (AP)

A month after convening a major meeting meant to welcome non­traditional families, Pope Francis told a gathering of global religious conservatives Monday that “children have a right to grow up in a family with a father and a mother.”

As has become the norm with Francis, experts began debating and parsing his comments at the Complementarity of Man and Woman conference. Was he trying to emphasize the primacy of traditional families or was he simply trying to support them as well?

Francis guaranteed even more attention to his controversial ministry to modern families by announcing Monday that he’ll make his first visit as pope to the United States next fall, for a conference on the subject.

Within an hour of the Vatican’s announcement that the pope would attend the World Meeting of Families in Philadelphia in September, hotels near his appearance sites reportedly were booked. Congressional leaders also have invited Francis to visit the U.S. Capitol and address a joint session of Congress.

Some pope-watchers said the United States — with its religiously diverse culture and large range of family types — is a perfect lab for Francis.

Pope Francis waves as he arrives to lead his weekly audience on Oct. 8 at the Vatican. (Max Rossi/Reuters)

“Where is the place for those people?” theologian John Grabowski asked Monday of the divorced, single-parent, same-sex or otherwise untraditional family. “He wants to say it is in the church, because the church has to be a place for everyone. And in the United States, we have this interesting thing where there’s a lot of engagement in religion, we have this ongoing debate about religion in public life and social experimentation about family, how to understand it. . . . He’s trying to engage them.”

Francis’s comment about the importance of a father and mother was widely shared on social media by some of the high-level faith leaders who attended, including Russell Moore, the public face of the Southern Baptist Convention, the country’s largest Protestant denomination.

Others in Rome for the meeting included Rick Warren, the California megapastor; Jonathan Sacks, former chief rabbi of the United Kingdom; and Anglican, Muslim, Pentecostal and Hindu leaders. For the first time, a top Mormon leader — Henry Eyring — was in official attendance at a Vatican conference.

Leaders came from Scotland, Pakistan, Nigeria, Iran and France to strengthen one another’s focus on traditional marriage as the key structure for preserving economic health and social order.

Also in attendance was Eugene Rivers, a prominent Pentecostal minister from Boston, and his wife, Jacqueline C. Rivers, who focus on the black church and the damage slavery has caused to black families.

“Pope Francis made clear that male/female complementarity is essential to marriage and cannot be revised by contemporary ideologies,” Moore tweeted. Moore is among those who have spoken out strongly against Francis for vague, all-inclusive comments that seem to water down the idea of a single Christian truth.

Explaining recently why he was participating in a conference at the Vatican — a blasphemous recognition of papal power to some non-Catholics — Moore said he saw common ground.

“I hope that this gathering of religious leaders can stand in solidarity on the common grace, creational mandate of marriage and family as necessary for human flourishing and social good,” he wrote.

Others saw something different — particularly in Francis’s decision to come to Philadelphia, the archdiocese of one of his most well-known U.S. critics, Archbishop Charles Chaput.

“It’s high politics,” said Sister Simone Campbell, an advocate and lobbyist on poverty and other social justice issues who has publicly challenged bishops on things such as health-care law. “I think he’s doing what he talks about: building peace. To build peace you can’t protect your space, your turf. You have to enter into a process of dialogue. He is boldly taking this to [conservatives] and engaging them in his very engaging way in conversation.”

She predicted that many nontraditional families will be visible in Philadelphia.

“He’s bringing in the various realities and letting people speak for themselves, and that creates change,” Campbell said. “He’s opening hearts. He’s not changing definitions.”

Francis opened his comments to the conference by examining its title. While the religious term “complementarianism” is widely understood to mean that men and women have different God-given roles, how that should play out varies widely. Does it mean wives shouldn’t work or question their husbands? How should it be applied to concepts of gender? The term is more widely used in evangelical circles, though even there it’s still debated.

“You must admit that ‘complementarity’ does not roll lightly off the tongue! Yet it is a word into which many meanings are compressed,” Francis said in his opening line.

His statement that children have a right to a father and mother was the only time the pope seemed to speak about heterosexuality. He was unspecific by what he meant about male-female complementarity.

“Let us not confuse that term with the simplistic idea that all the roles and relations of the two sexes are fixed in a single, static pattern. Complementarity will take many forms as each man and woman brings his or her distinctive contributions to their marriage and to the formation of their children — his or her personal richness, personal charisma,” he said.

The balance of man and woman is “a root of marriage and family,” the pope said. He emphasized the importance of a stable family as a place for development.

“For the family grounded in marriage is the first school where we learn to appreciate our own and others’ gifts, and where we begin to acquire the arts of cooperative living,” he said. “For most of us, the family provides the principal place where we can aspire to greatness as we strive to realize our full capacity for virtue and charity. At the same time, as we know, families give rise to tensions: between egoism and altruism, reason and passion, immediate desires and long-range goals. But families also provide frameworks for resolving such tensions. This is important.”

The conference Web site featured stylized short films of traditional families and the support they provide one another.

Grabowski, who is scheduled to address the Philadelphia conference with his wife, said debate about Francis’s meaning and intentions probably will stretch on for more than a year.

The conference that will take place in Philadelphia occurs every three years in different cities. In October, Francis convenes the second synod of top clergy, following the one last month, when recommendations will be made for potential changes to teachings or practices about the place of GLBT, divorced or cohabiting people — among others — outside of traditional marriage. After the second synod, Francis will pen an official document.

“So maybe in 2016 we can expect that kind of weighty statement on the family from him,” he said.

Francis characterized the breakdown of the traditional family as a symptom of a deeper problem with obligation.

“We now live in a culture of the temporary, in which more and more people are simply giving up on marriage as a public commitment,” he said. “This revolution in manners and morals has often flown the flag of freedom, but in fact it has brought spiritual and material devastation to countless human beings, especially the poorest and most vulnerable.”