VATICAN CITY (AP) -- They are stylistic opposites, one a bombastic tycoon-turned-president, the other a famously modest pope. They disagree openly on such weighty issues as immigration, climate change and economic policy.
But President Donald Trump and Pope Francis share a trait that adds drama to their first meeting Wednesday: unpredictability. And when they greet each other - in a Vatican ceremony laden with history and symbolism - they may well find common ground, particularly in denouncing religiously inspired violence and demanding Muslim leaders take a greater stand in rooting out fanaticism from their places of worship.
To reach public harmony, the two men, unquestionably two of the most famous figures on the planet, will have to set aside their past and very public conflicts.
When Trump took his oath of office on Jan. 20, Francis sent him a telegram of congratulations, offering his prayers for wisdom and strength that the new president's decisions would be guided by ethical values.
"Under your leadership, may America's stature continue to be measured above all by its concern for the poor, the outcast and those in need, who, like Lazarus, stand before our door," the message read.
It was a subtle reminder that the two leaders had gotten off to a very rocky start over their different views on migration. Francis early last year was sharply critical of Trump's campaign pledge to build an impenetrable wall on the Mexican border and his declaration that the United States should turn away Muslim immigrants and refugees.
"A person who thinks only about building walls, wherever they may be, and not building bridges, is not Christian," Francis said then. The pontiff has been a vocal advocate for aiding refugees, particularly those fleeing the violence in Syria, deeming it both a "moral imperative" and "Christian duty" to help.
Trump has never been one to let an insult, perceived or real, go by without a response, and he made no exception for the world's best-known religious leader. He called Francis "disgraceful" for doubting his faith.
Trump's visit to the Vatican is the third leg of his tour of the world's three main monotheistic religions, coming after he visited the cradles of Islam and Judaism. While pope and president differ on many social and economic issues, the two are preaching from the same playbook in demanding that Muslim leaders take a greater stand against extremists in their mosques and communities. It's likely that both sides will seek to highlight such common ground after their Wednesday morning audience.
In Saudi Arabia on Sunday, Trump implored Middle Eastern leaders to extinguish Islamic extremism from the region and described it as a "battle between good and evil" rather than a clash between the West and Islam. Those words echoed what Francis said in a trip to Egypt last month as the pope demanded the country's imams teach their young to reject the use of violence in God's name and backed an Egyptian government crackdown on Islamic militants who have increasingly targeted the country's Christian community.
"As religious leaders, we are called to unmask violence that masquerades as purported sanctity," Francis said April 28 at Cairo's Al-Azhar, the revered, 1,000-year-old seat of Sunni Islam learning that trains clerics and scholars from around the world.
Both Trump and Francis expressed dismay at Monday night's deadly blast at a concert in Manchester, England, with the president adding a shot at the suicide bomber who detonated it.
"So many young, beautiful innocent people living and enjoying their lives, murdered by evil losers in life," Trump said.
The pope expressed "heartfelt solidarity with all those affected by this senseless act of violence," especially the "children and young people" who died. He made no mention of anyone responsible.
While Trump and Francis may be in brief agreement on a need for Muslim leaders to do more against extremists, the president's prior anti-Muslim rhetoric - including his musing that Islam "hates" the West - is the antithesis of what the pope has been preaching about a need for dialogue with Muslims. Francis also differs sharply with Trump on the need to combat climate change and economic inequality, but they are unlikely to air their differences publicly and Francis has said he wanted to find common ground in the meeting.
Last week, the pope said he'd "never make a judgment about a person without hearing him out" when asked about the president.
"I think they may be a little less different than we think," said Joseph Capizzi, a professor of moral theology at the Catholic University of America. "While the pope emphasizes humility, he, like Trump, is a savvy media personality. He and Trump both are effective at using the media. Instead, I think their agendas really don't converge much, and thus I don't see much opportunity for working partnership."
Papal visits with heads of state are carefully arranged bits of political and religious theater that follow a specific program, with little room for deviation or unwanted surprises. Trump will be given a tour of the Vatican after he arrives and will then first meet with the pontiff in his library. The two men will then be left alone with a translator to hold a private discussion before emerging again to exchange gifts and farewells. Trump will also view the Sistine Chapel.
Trump will be the 13th president to visit the Vatican. Francis got along exceedingly well with Barack Obama, and they had lengthy meetings both in Rome and Washington, as the former president praised the pope as a beacon of social justice. Other presidents and popes have also shared goals, including Ronald Reagan and Pope John Paull II who were united in their hopes for the defeat of communism.
But most papal experts believe that there is little chance of a long-lasting alliance between Trump and Francis, even if the carefully scripted meeting goes well.
"Pope Francis' political and pastoral priorities do not line up easily with those of the Republican Party in general and Trump in particular," said the Rev. James Bretzke, a professor at Boston College.
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