Cardinal Roger Etchegaray, who helped organise the first Assisi day in 1986, said John Paul II had been careful to avoid mixing beliefs, and Benedict XVI was no different.
"Interreligious dialogue has spread" over the last 25 years, and the pope sees it "as a common, irrevocable heritage of Christian sensibility," he said.
The pope's main aim is for participants to agree to "a common commitment to reject the instrumentalism of religion and the use of violence in the name of God," said a Vatican insider.
Number two of the Pontifical Council for Interreligious Dialogue, Pier Luigi Celata, said the problems that particularly concern religions are immigration, cultural diversity, religious liberty and the defence of the family.
"These issues oblige faithful people from different religions to look for common solutions," he said.
At the end of the day of talks, the main participants will renew their commitment to peace in the square in front of St. Francis' Basilica.
A burning torch will be symbolically presented to the delegations in the hope that they will take the message back with them to their communities.