Pope Francis will dine with about 90 prisoners who won their spots after a raffle among some 1,900 detainees.
Cardinal Luis Antonio Tagle of Manila, Philippines, has been named the new president of the Catholic Biblical Federation.
While Tagle was elected unanimously as head of the federation at an Oct. 24-25 meeting in Rome of its executive committee, Pope Francis confirmed his election March 5.
He will assume his office at the federation's plenary assembly, to take place June 18-23 in Nemi, Italy. Tagle will succeed Italian Archbishop Vincenzo Paglia, who has been president of the Catholic Biblical Federation since 2002.
"It's like a little vague feeling. But I have the feeling that the Lord puts me [here] for a brief thing and not more."
"Respect for the dignity of every human person and the common good are the two pillars on which the position of the Holy See has developed."
Over the centuries, the international community has developed criteria for determining whether a war is just and for regulating conduct in combat; now it needs clearer guidelines for "humanitarian intervention" and for post-conflict reconciliation, said the Vatican secretary of state.
Cardinal Pietro Parolin, Pope Francis' top aide and chief coordinator of the Vatican diplomatic corps, also warned against indifference toward situations of conflict around the world.
Shot dead while celebrating Mass in 1980, Romero has long been considered a saint by many in Latin America, but the official Vatican process of sainthood lingered.
Bishop Fridolin Ambongo Besungu said the changes to the Vatican seem "like a change not only in attitude here, but a new anthropology for the way of living our faith."
Allowing priests to celebrate Mass in the language of the local congregation rather than in Latin allowed the faithful to understand and be encouraged by the word of God, Pope Francis said.
"You cannot turn back. We have to always go forward, always forward and who goes back is making a mistake," he told parishioners after commemorating the 50th anniversary of the first time a pope celebrated Mass in the vernacular following the Second Vatican Council.
As the second anniversary of Pope Francis' election approached, an international group of philosophers, sociologists and theologians gathered to discuss how to renew the church in a secular age; many said that is exactly what Pope Francis is doing.
"I think the church had gotten into the stance of defending itself against its critics and trying to convince them, but that's not a stance of dialogue. Pope Francis is going out and reaching out," said Charles Taylor, professor emeritus of philosophy at Canada's McGill University.
The Italian government is on high alert after threats from the Islamic State called Italy "the nation signed with the blood of the cross."
Italy is one of a handful of major Western counties that has not been victim of a large-scale terror assault since the Sept. 11 attacks in the U.S.
Italian officials fear extremists could enter the country amid the growing tide of refugees arriving by boat from North Africa. About 500 extra troops have been stationed to guard symbolic targets in Rome and monitor the streets of the capital for suspicious activity.