Pope Benedict XVI has been forced to cancel a visit to the prestigious La Sapienza University in Rome after lecturers and students expressed outrage at his past defence of the Catholic church's actions against Galileo.
The Pope had been due to make a speech at the university on Thursday 17 January 2008. The Vatican has dismissed some of the protestors as anti-clerical activists, and have said that others have misunderstood Benedict's remarks, made 17 years ago.
A professor of genetics at La Sapienza has called the attempts to prevent the Pope from speaking "shameful" and a violation of the intellectual freedom they claim to uphold.
Nevertheless, there is no doubt but that the Vatican is extremely embarrassed by the incident, which will strengthen the hand of those who argue that religious belief and scientific enquiry are incompatible - a view rejected by those involved in science-theology conversations, but spreading widely among non-specialists.
Sixty-seven academics have said that the Pope effectively condoned the 1633 trial and conviction of the astronomer Galileo for heresy, in remarks he made while head of the Sacred Congregation for the Doctrine of the Faith, the successor to the notorious Inquisition.
As Cardinal Josef Ratzinger, Pope Benedict said that Galileo had turned out to be correct about the earth revolving around the sun, and that subsequent biblical scholarship had rejected literalist readings of texts that had been taken by the Church to deny this.
Nevertheless, he said, Galileo had been dogmatic and sectarian in his statements at the time, and the Church authorities had acted reasonably given the levels of knowledge available then.
But the scientists say that this is "insulting" and unacceptable equivocation. The Church was unjust, irrational and unfair in its treatment of their predecessor and its outright rejection of Copernican theory, they say.
The Vatican insists that the Pope is in no way "anti-science", and points out that the Vatican Observatory is now at the forefront of research in the field of modern astronomy, promoting conferences where the consonance of sciencitific enquiry with theological learning is regularly on display.
But in light of the protests they have decided it would be better for the Pope not to attend the meeting, though his speech will be read on his behalf.
Pope Benedict was in charge of Roman Catholic doctrine in 1990 when, as Cardinal Ratzinger, he commented on the 17th-Century Galileo trial. Fifteen years ago Pope John Paul II officially acknowledged that the Church had been wrong about Galileo's theories and issued a reversal of his condemnation.
It amounted to an apology, but a rather guardedly constructed one, said observers.
"In the name of the secular nature of science we hope this incongruous event can be cancelled," said the protest letter addressed to the university's rector, Renato Guarini.
In a separate initiative, students at La Sapienza organised four days of protest this week. The first revolved around an anti-clerical meal of bread, pork and wine, the BBC's Christian Fraser has reported from Rome.
Bruno Dalla Piccola, professor of genetic medicine at the university, said the protests were "a shameful episode which do no credit to a great and important university".
Both professors and students should be ashamed of themselves for trying to prevent someone who "enjoys respect at a world level" from speaking, Professor Dalla Piccola said, adding "Perhaps they are afraid of what the Pope has to say".