Why did some traditionalist Catholics criticize the Assisi prayer meeting?

In 1986, Pope John Paul II invited leaders of major world religions to Assisi, Italy, for a universal prayer service dedicated to world peace. While intended as a gesture of interfaith dialogue, the event faced significant backlash from traditionalist Catholics and ultraconservatives of other faiths.1

Traditionalist critics, most notably Archbishop Marcel Lefebvre, condemned the meeting as a "scandal" and a betrayal of "the one true faith". These critics viewed the gathering as an act of religious indifferentism—a concern historically associated with the Roman Catholic Church's hesitation toward the broader ecumenical movement. For Lefebvre, the Assisi meeting served as a primary justification for his decision to consecrate bishops without papal approval in 1988, an act that led to his excommunication and marked a significant schism within the Church following the reforms of the Second Vatican Council.12