Now the Pope must make good on his promise and help the peace agreed to on paper become a reality in the hearts of a divided Colombia.
"The Vatican has made it very clear that the Holy Father is not going to Colombia to bless the peace process or support either the government or the opposition," said Nestor Ponguta, a longtime Vatican correspondent for W Radio Colombia and the author of a book on Pope Francis.
"The great hope for his visit is that it helps us to heal the wounds, and that the message extends to other countries like Venezuela that are experiencing very difficult conflicts."
The Pope and Vatican diplomacy have been working for several years to help Colombia achieve peace.
In December, Francis personally brought together Santos and opposition leader, former President Alvaro Uribe, in an unprecedented three-way meeting at the Vatican.
The Pope publicly called on Colombia's leaders to push forward on the path to peace from Havana's Revolution Plaza during a visit to Cuba in 2015. "We do not have the right to allow ourselves yet another failure," he said.
The 52-year civil war in Colombia, the longest in Latin American history, has claimed 220,000 lives and displaced millions.
Former US Secretary of State John Kerry officially recognized Francis' role in helping to end the conflict.
Though the focus is on peace, Vatican officials say the Pope's visit is about much more.
"This trip is daring and important," Guzman Carriquiry, vice president of the Vatican's Commission for Latin America, said at a Vatican briefing Friday. "It is wrong to only focus on peace; the Pope sees this trip as part of a long process in fighting violence."
Carriquiry pointed to some causes of the violence. "Over 50% of (the) Colombian population live in poverty; the drug trafficking culture poisons and creates corruption in the life of the country."
During his visit, Francis will stay at the papal ambassador's residence in Bogota and take day trips to Villavicencio, Medellin and Cartagena.
The Pope will participate in a prayer meeting for national reconciliation Friday in Villavicencio with some 6,000 victims of violence, former fighters and militia.
At Mass on Friday, Francis will beatify two Colombian priests who were killed in violence.
Bishop Jesus Emilio Jaramillo Monsalve of Arauca, was shot twice in the head by rebels in 1989 and the