The trigger was a lecture by the Swiss Jesuit Mario Imperatori, who teaches in Naples.
In his remarks, he had asserted a similarity between Israel's actions in the recent Gaza war and the genocide of the Jews in the Third Reich.
In spontaneous reactions from the audience, visibly angry Jewish participants from Israel and the US spoke of a "dark moment" and a "sad low point" for the Judeo-Christian dialogue.
The occasion of the congress at the Pontifical Gregorian University is the 60th. anniversary of the publication of the Council document "Nostra aetate", in which the Catholic Church had rearranged its relationship with Judaism and other religions.
The congressional leadership, appointed by Gregoriana University, sought to smooth the waves and called for compliance with the standards of an academic debate.
At the same time, the Bureau distanced itself from some of Imperatori's remarks.
The trade congress with representatives of several world religions is scheduled for three days.
A detailed debate on the Judeo-Christian dialogue is on the agenda for Wednesday afternoon.
A meeting of the participants with Pope Leo XIV is scheduled for Tuesday evening.