Pope Francis waves to the crowd as he arrives in the popemobile at Bolivar Square in Bogota, Colombia, on Thursday. (Jose Jacome/EPA-EFE)

BOGOTA, Colombia — Pope Francis on Thursday pressed a message of reconciliation as he began a five-day trip through Colombia, a country scarred by more than 50 years of internecine conflict and struggling to implement a fresh accord with Marxist rebels.

In a morning address at the presidential palace, he acknowledged the “obstacles, differences and varying perspectives” complicating that effort but urged Colombia’s political and civic leaders to persevere.

“The more demanding the path,” Francis said, “the greater must be our efforts to acknowledge each another, to heal wounds, to build bridges, to strengthen relationships and support one another.”

Later, hundreds of thousands of people streamed through the streets to the capital’s Simón Bolívar park, where Francis was scheduled to celebrate Mass. Some carried packed lunches and plastic stools, and many waved white and yellow flags decorated with the Vatican crest.

“This isn’t just about a message of peace and reconciliation,” said 70-year-old Fernando Soler, who marched along wearing a baseball cap bearing Francis’s image. “This is about the peace processes, too.”

After decades fighting to topple the government, the country’s main rebel group — the Revolutionary Armed Forces of Colombia, or FARC — laid down its arms in June and, as part of an accord signed last November, transitioned into politics. Last week, it wrapped up its first political convention and launched a party under a repurposed acronym: FARC now denotes the Alternative Communal Revolutionary Force.

Meanwhile, a temporary cease-fire between security forces and Colombia’s second-largest rebel group, the ELN, is due to take effect Oct. 1.

“The pope is coming at a unique moment in our history,” President Juan Manuel Santos said Monday as he announced the ELN cease-fire. “Right when we turn the page on an absurd conflict and face the future with hope.”

But the country remains split over the scope of the deals reached with the rebels, who were responsible for numerous atrocities during the decades of conflict. In a referendum last year, half of Colombians opposed the accord with FARC, forcing a change of terms, and many now are looking to the pope for spiritual guidance.

“He’s got a challenge here. He’s got to overcome the polarization between friends and enemies of the peace process, but without seeming like an outright defender of President Santos,” said the Rev. Fernán González, a Jesuit priest and researcher at the Bogota-based think tank CINEP.

“Francis is smart, good at maneuvering himself in these diplomatic situations, but these are very turbulent waters,” he added.

Before setting out on his trip, the pope indicated he is aware of the challenges. “Let’s take the first step,” he said from the Vatican on Monday. “Peace is what Colombia has been working to find for a long time now.”

On Wednesday, Maricela Sabogal, 56, said she was prepared to reconsider her view of the peace process as she waited in the crowd for a glimpse of the pope as he was driven to the Vatican residence here.

“I voted no against the peace accord last year,” she said. “But if he comes and gives the accords his blessing, sure, I’d probably be more forgiving.”

The mistrust of Santos’s policies runs deep.

The deal that the president negotiated with FARC lets rebel leaders avoid prison time if they confess to their crimes in a special tribunal. It also grants them eligibility for a minimum of 10 congressional seats in next year’s elections — even if they don’t have all the votes they need. Some clergymen and political leaders view the peace process as tarnished by impunity.

“We agree on generous treatment for the rank and file guerrillas who follow through on their commitments,” opposition senator and ex-president Alvaro Uribe wrote to the pope recently. “But that’s an issue that we separate from total impunity for its leaders.”

Francis isn’t the first leader of the Catholic Church to try to heal Colombia’s scars of war. Pope John Paul II visited the country in 1986, just months after talks between FARC and Belisario Betancur’s government broke down. That year was also the eve of a violent assassination campaign against leaders of FARC’s political wing. The assassinations forced some of FARC’s leaders back into the jungle, where military tactics seemed to them like the only solution.

It’s different this time, according to Victor De Currea-Lugo, a professor of armed conflict studies at Colombia’s National University. “John Paul II played a role in pulling down the Berlin Wall — so the Communists sort of distrusted him,” he said.

“The FARC had momentum in the 1980s. They weren’t as stained by drug trafficking. And they weren’t as worn out as they are now. They were still the Robin Hoods of the day.”

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Argentine-born Francis, a Jesuit whose real name is Jorge Mario Bergoglio, appears to have a special Latin America checklist within his papal mandate. Together with President Barack Obama, he helped unfreeze diplomatic relations between Cuba and the United States in 2015. Earlier this year, he turned to Venezuela’s political crisis, hoping to broker a deal between President Nicolás Maduro’s government and opposition leaders.

“Now that he’s supporting negotiations in Venezuela, it’s bothering some friends in Colombia. And they’ve given him some heat for that,” González said.

Part of Francis’s mission here will be to reconcile members of Colombia’s opposition to Santos’s policy initiatives, which they see as the first step on a slippery path to Venezuelan-style authoritarianism.

The pope’s Latin American roots matter, according to González, who says he might have more luck than his predecessors in helping resolve Colombia’s conflict. “As a Latin American, he really understands the problems of our region,” he said. “He sees why there are internal conflicts.”

In Bogota on Thursday, the pope stressed that Colombia also needs to enact “just laws” to address the structural causes of poverty and inequality. “ Let us not forget that inequality is the root of social ills,” he said.

Francis will celebrate Mass in Villavicencio on Friday before visiting Medellin, a city plagued by its history of drug wars. He will end his trip with a visit to Cartagena, where some Jesuits expect him to promote racial inclusiveness and tolerance. The city was a slave port in colonial times.