Pope Francis on Sunday inaugurated a gathering of nearly 200 bishops and cardinals who will tackle the thorny themes of sex and marriage, placing the popular pontiff in the midst of a battle between theological conservatives and liberals within the Roman Catholic Church.
Francis summoned the extraordinary Vatican synod after a survey he ordered last year revealed that many churchgoers are ignoring the church's ban on birth control and want it to minister to gay couples.
Francis put hard-liners on notice last year by saying the Vatican should not be "obsessed" with issues such as homosexuality, abortion and contraception.
The synod is not expected to change doctrine on those issues, but may focus on the row raging within the church over the ban on giving communion to Catholics who divorce and remarry. The church does not recognize civil divorces and considers such people to be living in sin.
Moves to drop the ban have sparked a backlash from conservatives, who say it would contradict Jesus' teaching on the permanence of marriage.
Asked about the ban last year, Francis hinted at change when he said, "I believe that this is the season of mercy."
In a Mass at St. Peter's Basilica on Sunday, he may have been referring to overly rigid rule-making when he warned that "evil pastors lay intolerable burdens on the shoulders of others, which they do not lift a finger to move."
In an address to tens of thousands gathered in St. Peter's Square on Saturday evening, Francis urged synod participants to listen to "the call of the people," to "lend an ear to the rhythm of our time" and to smell the "odor" of modern life.
German Cardinal Walter Kasper — a close ally of Francis' — told a meeting of cardinals in February that communion for remarried divorcees would give them a "spiritual life raft."
If the church can forgive murderers, he has argued, it can forgive people whose marriages fail.
Five senior cardinals, including the Vatican's doctrinal watchdog, Cardinal Gerhard Mueller, responded with a book objecting to any rule change, prompting Kasper to claim that church conservatives were plotting a "doctrinal war" at the synod, with Francis as their likely target.
In an interview last week, Cardinal Raymond Burke, the American head of the Vatican's supreme court and one of the authors of the book, appeared to challenge Francis to make his views clear at the synod.
"I have to say that I find it amazing that [Kasper] claims to speak for the pope," he said. "The pope does not have laryngitis. The pope is not mute. The pope can speak for himself."
But Father Thomas Reese, a Vatican analyst at the National Catholic Reporter, said Francis might prefer to listen rather than speak at the synod.
"He really wants to hear what people think," he said, adding, "Francis would not want to make a quick decision that would split the church."
One compromise observers have said Francis may propose would be to make it easier to get a Vatican-recognized annulment — an alternative to civil divorce.
Apart from the 191 prelates present at the synod, about 60 other experts and lay people will attend, including married couples who will discuss their lives.
After a week of speeches, attendants will hold private meetings before a final document is handed to the pope.
Although the gathering is not expected to change the rules on divorce, its conclusions will feed into a synod to be held next year, which may act.
"This synod is only the beginning of a process," said Reese. "The church is like the Queen Mary — it can't turn on a dime when it comes to church teaching."