ROME— A brief talk at a Vatican conference on Friday by Democratic presidential candidate Bernie Sanders has stirred plenty of controversy, with some accusing Sanders of seeking to exploit the Vatican or the pope for a photo-op, others charging the Vatican with injecting itself into U.S. politics, and others just finding the whole thing either puzzling or amusing.

His talk, scheduled for 4 p.m. Rome time (10 a.m. on the East Coast), is titled “The Urgency of a Moral Economy: Reflections on the 25th Anniversary of Centesimus Annus.”

Before the talk, it’s worth recapping what Centesimus Annus is, who invited Sanders, and who else is coming to the conference.

The document

Centesimus Annus (“On the Hundredth Anniversary”) is a social encyclical published by St. John Paul II in 1991. It examines the role of the state and the economy from the perspective of Catholic moral theology, following the collapse of the Soviet Union.

It built on other milestones in papal social teaching such as Leo XIII’s Rerum Novarum in 1891, which addressed the rise of industrial capitalism; Pius XI’s Quadragesimo Anno in 1931, which came during the Great Depression; and Populorum Progressio, Paul VI ‘s 1967 document reflecting on the ferment of decolonization.

Centesimus Annus marked the 100th anniversary of Rerum, hence its title.

The document is considered a turning point, the first papal social encyclical to clearly endorse the market economy as the best way to foster “free human creativity in the economic sector,” without extolling laissez-faire capitalism.

The event

Sanders is speaking at an event called “Centesimus Annus: 25 Years Later,” planned not as a commemorative event but a “serious academic discussion” of the encyclical’s impact and legacy.

The papers presented at the April 15-16 conference aren’t intended to be pious recollections of the late pope, or celebrations of his other political achievements such as helping to unify Europe by playing a role in bringing down the Berlin wall.

The symposium will instead focus on two major issues:

• The changes in the world situation – economically, politically, and culturally – over the past 25 years.
• The engagement of Catholic social teaching with the world, in order to evaluate how the Church can improve its engagement in this field in the coming decades.

Who’s behind the invite

Despite some early headlines, Pope Francis wasn’t behind the invitation. It was, however, another Argentine in Rome, with a world-renowned American economist in the mix.

The event is being organized by the Pontifical Academy for Social Sciences (PASS), headed by Argentine Bishop Marcelo Sanchez Sorondo, in collaboration with the Institute for Advanced Catholic Studies, at the University of Southern California.

As Sanchez Sorondo put it in the official statement he released amidst the brouhaha the invitation generated, the PASS was established by John Paul II in 1994 “with the aim of promoting the study and progress of the social sciences, primarily economics, sociology, law and political science.”

Since Francis’ election in 2013, Sanchez Sorondo has been the go-to man for some of the pope’s main social concerns, organizing workshops, conferences and symposiums on an array of issues such as human trafficking and modern day slavery, climate change, popular movements, education, and migration.

But the word in Rome is that it wasn’t so much the prelate who first had the idea of inviting the U.S. Senator, but Sanders’ foreign policy adviser, American economist Jeffrey Sachs, who’s been a regular at PASS events over the last three years.

Sachs, a Columbia University professor and UN advisor, acknowledged to several newspapers that he’d helped the Vatican reach out to Sanders in March, and denied accusations by Margaret Archer, president of the academy, who’d told Bloomberg that the candidate’s campaign had requested the invite.

For the record, Sanchez Sorondo has already denied Archer’s allegations in an interview with Reuters, saying that she’d known about the invitation from the start.

Who else was invited

The two-day symposium also includes in the line-up Cardinal Oscar Andrés Rodríguez Maradiaga of Honduras, Ecuadorian President Rafael Correa, Bolivian President Evo Morales, and Italian politician and philosopher Rocco Buttiglione.

The Vatican has tried to distance itself from Sanders’ invite to the meeting, with a spokesman repeatedly denying Francis’ involvement. Sources at the PASS have told Crux that even participation from the pope at the gathering is “improbable,” particularly seeing that he’s headed to the Greek island of Lesbos on Saturday to make a pro-immigrant statement.

Then there’s the political differences between Sanders and the pope, which the Vermont senator acknowledged in an interview with MSNBC last Friday.

“He has played an unbelievable role of injecting moral consequence into the economy,” he said, adding that yes, he and the pope don’t agree on abortion and gay rights.

The invitations for both Morales and Correa have also raised some eyebrows, not necessarily for opposing Church teaching – Correa has actually threatened to resign if a bill legalizing abortion were to pass in Ecuador – but because they’re know critics of their local Catholic hierarchies.

Morales is a political leftist who describes himself both as a Catholic and a practitioner of Bolivia’s ancestral polytheistic indigenous Andean cult. He is a self-declared “Francis fan” but he has also ridiculed his local bishops, often accusing them of being part of a right-wing oligarchy, “medieval,” and intent on revisiting the inquisition.

Local bishops have repeatedly condemned the growth of organized crime, drug dealing, despotism, and the persecution of the political opposition under Morales, with the president testily suggesting they “stick to saving souls”.