Ankara, Turkey - He was the first pope to visit a mosque and pray at Judaism's holiest site, and he returned the relics of revered Orthodox Christian saints.
In death, John Paul II continues to set precedents: His funeral is attracting religious and political leaders whose faiths were never represented at such a high level at papal burials.
John Paul II ushered in "the globalization of religion," said John Esposito, founding director of the Georgetown University Center for Muslim-Christian Understanding in Washington. "He increased exponentially the dialogue with ... people of all faiths."
Friday will mark the first time the leaders of Orthodox Christianity and the Armenian Apostolic Church have attended a pope's funeral. Iran and Syria are sending their presidents, and Israel is dispatching its foreign minister - top levels of representation never before seen at papal funerals.
The funeral is making its mark even in places where the pope has virtually no following. In Turkey, a country with a small number of Roman Catholics, the national police have canceled celebrations of the force's 160th anniversary. Turkey's flag, which features the crescent, a symbol of Islam, will fly at half mast Friday to honor the pope.
"Not only was he the leader of the Catholic world, he was also the leader for peace and dialogue between religions," Turkish Prime Minister Recep Tayyip Erdogan said Thursday before flying to Rome for the funeral. "Even toward the end, at the height of his ill health, he relentlessly worked toward that goal."
Ali Bardakoglu, Turkey's top Islamic cleric, said he shared "the grief of Catholics worldwide."
The pope's ability to bridge the divide between religions was aided by his common touch and keen understanding of the power of symbolism, which inspired even those who sharply disagreed with him on issues of faith. Many people seemed to warm to the pope and regard him as genuinely holy even if they did not share his religious beliefs.
The note he slipped into a crack in the Western Wall apologizing for the suffering of Jews over the centuries has been preserved in Israel's national Holocaust museum.
The gesture marked a crucial change from Pope Paul VI's visit to Israel in 1964, when the Jewish state and the Vatican were so distant the pope traveled only to Christian holy sites and never mentioned Israel by name.
The pontiff's contribution to religious tolerance "will be with us for many years," Israeli Prime Minister Ariel Sharon said at the start of a Cabinet meeting last week.
For many Muslims, a key symbolic moment was when the pope stood in the ancient Omayyad Mosque in Damascus, Syria, in 2001 and appealed to Christians and Muslims to seek common ground rather than confrontation.
For the world's 300 million Orthodox Christians, the pope's landmark apology for Roman Catholic wrongs against the Orthodox and his return of the relics of two Orthodox saints were no doubt key to the decision of Ecumenical Patriarch Bartholomew I - leader of the world's Orthodox Christians - to attend the funeral.
"Pope John Paul II envisioned the restoration of the unity of the Christians and he worked for its realization," said Bartholomew. "His death is a loss not only to his church, but to all of Christianity as well, and to the international community in general, who desires peace and justice."
John Paul's global reach is due in part to the fact that he was history's most-traveled pope - logging 723,723 miles, or three times the distance to the moon. His message was reinforced by a modern media that beamed his smiling image to millions of homes.
"Pope John Paul in many ways became a leader and symbol to a degree that no pope in the past could achieve," Esposito said. "It is a product of the man ... but also the fact that with globalization of travel and communications he could play that role."
Besides Bartholomew, key religious leaders at the funeral will include the head of the Armenian Apostolic Church Catholicos Karekin II, Archbishop of Canterbury Rowan Williams, Lebanon's Maronite Christian Cardinal Nasrallah Sfeir, Religious Affairs Minister Maftuh Basyuni of Indonesia and Shear-Yishuv Cohen, the chief rabbi of the Israeli city of Haifa. Teoctist, the 90-year-old patriarch of the Romanian Orthodox Church was planning to attend but will not because he has the flu.
There are some who will not be joining in the mourning.
"How can the death of a non-Muslim be a loss to the Muslim world?" asked Gamal Sultan, an Egyptian Islamic activist and editor of Al-Manar, a journal that serves as a mouthpiece of Islamic fundamentalists.
Although Israel is sending its foreign minister, the country's two chief rabbis are not attending. And Saudi Arabia, home to Islam's holiest shrines, has not announced it will send anyone.
Left open by the death of the pope is whether his legacy of promoting interfaith dialogue will continue.
"A lot depends on the next pope," Esposito said. "There is a momentum there and part of that momentum cannot be reversed."