Bernie Sanders launched one of the most powerful indictments of modern capitalism of his campaign in the Vatican on Friday, saying that the greatest challenge facing the world was a moral imperative to redirect “our efforts and vision to the common good”.

The sweeping remarks were delivered in the shadow of St Peter’s dome, about an hour after the Democratic presidential candidate touched down in Rome for a short stay in the Eternal City to take part in a Vatican-sponsored academic conference.

Sanders praised the Roman Catholic church for its consistent social teachings on economic matters, saying: “There are few places in modern thought that rival the depth and insight of the church’s moral teachings on the market economy.”

But his most effusive praise was reserved for Pope Francis, whom he heralded for raising the “most profound issues” of the day – from the problems of the dispossessed, to the loneliness of the elderly who cannot afford their medication, to the challenge of climate change – with a “vision and articulateness”, while others chose to ignore the issues.

The pope, he said, had tapped into an “instinctual” belief held by many that there was something “profoundly wrong” with society today.

“I have been enormously impressed with Pope Francis speaking out and his visionary views about creating a moral economy, an economy that works for all people, not just the people on top,” Sanders told a group of reporters who had gathered just outside the Vatican gates.

“And what he has said over and over again: we cannot allow the market just to do what the market does, that is not acceptable.”

For all his apparent love of the pope, there was no meeting scheduled between Sanders and the 79-year-old Argentinean, who – not unlike the Democratic leftwinger – has cast himself as the great reformer of an unwieldy bureaucracy fighting ingrained interests. For Vatican watchers, the decision to avoid a meeting – though many believed one could still happen in the final hour – was a classic Francis move, given the pope’s reluctance to be seen as a political operator.

Sanders seemed to relish adopting some of the damning language Francis himself has used to describe the harm of “unfettered capitalism”, which the Argentinean pontiff has denounced as “the dung of the devil”.

Alluding to the words of Pope Leo XIII over a century ago that pointed to the “enormous wealth of a few as opposed to the poverty of the many”, Sanders said the situation was far worse today.

“At a time when so few have so much, and so many have so little, we must reject the foundations of this contemporary economy as immoral and usustainable,” he said.

Sanders also pointed to the “unheeded” warnings of Pope John Paul about the “excesses of untrammelled finance”, which he said had been “deeply prescient” following the fall of communism in eastern Europe.

“Speculation, illicit financial flows, environmental destruction, and the weakening of the rights of workers is far more severe than it was a quarter century ago,” Sanders said. “Financial excesses, indeed widespread financial criminality on Wall Street, played a direct role in causing the world’s worst financial crisis since the Great Depression.”

Sanders delivered his remarks at the Pontifical Academy of Social Sciences, at an academic conference which also hosted the Bolivian president, Evo Morales, and the Ecuadorian president, Rafael Correa.

He told gathered journalists that the decision to come to Rome had taken him off the campaign trail at home “for a day” – though it was more like two days given the travel – but said he had been enormously excited to receive the Vatican’s invitation.

A note from Pope Francis was read during the conference in which the pontiff apologised for his absence. Saying he had envisaged coming to the conference at 7pm, the pope said he realised that his attendance would be “very complicated” because of a trip to Lesbos he had scheduled for Saturday.

Bernie Sanders fans at the Vatican. Photograph: Stephanie Kirchgaessner/The Guardian

A small group of American Sanders fans living in Rome descended on the Vatican for the occasion. Holding a sign that read “Rome is Berning”, supporter Linda Lauretta, a native of New Jersey who spent years in upstate New York before her move to Rome two years ago, swore that she would get involved in a write-in campaign for Sanders if he was not the Democratic nominee.

“I won’t vote for Clinton. For several elections now I’ve voted for the lesser of two evils,” she said. “Not doing that any more.”