ANKARA, Turkey (AP) -- Bartholomew I, the spiritual leader of the world's Orthodox Christians, will attend Pope Francis' installation Mass -- the first time a patriarch from the Istanbul-based church has attended a papal investiture since the two branches of Christianity split nearly 1,000 years ago.
Bartholomew said he is doing that to underscore the importance of "friendly ties" between the churches and expectations that the new pontiff will advance rapprochement efforts that began decades ago.
It's a sentiment that many leaders of other faiths are expressing ahead of Tuesday's installation, which is drawing dozens of Jewish, Orthodox and other Christian leaders to Rome for the start of a pontificate that is poised to deepen the Vatican's ecumenical and interfaith efforts given Francis' namesake and own history.
Those who knew Jorge Mario Bergoglio as leader of Argentina's Catholic Church say promoting interfaith dialogue was at the heart of his view of the what the Catholic faith should be about -- an outward-reaching, bottom-up effort to improve lives, no matter what people's faith.
"He's the one who opened the cathedral of Buenos Aires for interfaith ceremonies, like when we prayed for peace. He's not one of those who waits for you to call them to participate in these events -- he promotes them," Buenos Aires Rabbi Alejandro Avruj told The Associated Press on Monday.
Bergoglio brought Jewish, evangelical Christian, Greek Orthodox and Muslim leaders into the Metropolitan Cathedral to pray for peace in the Middle East. Last November, he welcomed Jews for a joint service on the 74th anniversary of Kristallnacht, the night in 1938 when nearly 200 synagogues were destroyed, Jewish shops were looted and tens of thousands of Jews were sent to be exterminated in Adolf Hitler's Germany.
He also sponsored interfaith prayers after Pope Benedict XVI offended Muslims in 2006 by quoting a Byzantine emperor as saying some of the Prophet Muhammad's teachings were "evil and inhuman." Rather than criticize Benedict directly, Bergoglio let a lower-ranking priest lead that service and did not himself participate.
Bergoglio also shared happier moments -- such as lighting the first candle in a Jewish Hanukkah ceremony in December, his latest interfaith act.
"He spoke of light as renovation, of the re-inauguration of the temple of Jerusalem 2,200 years ago, and the need to carry light to the world," Avruj said. "He's got a very deep capacity for dialogue with other religions."
Bergoglio's ecumenical outreach will surely be boosted by the presence of Bartholomew, who met with his two predecessors on several occasions but didn't attend their installation.
The Russian Orthodox Church's Patriarch Kirill is staying home in Moscow and sending his envoy instead. That church's spokesman, Metropolitan Hilarion, said any possible meeting between Francis and the Russian patriarch "will depend on how quickly" they can settle lingering disputes over properties following the collapse of the Soviet Union and Moscow's objections to what it sees as Catholic efforts to gain followers in traditional Orthodox lands.
Bartholomew, however, said he's attending the installation Mass to underscore the importance of building on closer ties that began decades ago, and because he has hopes for the modest pope from Argentina.
"It is a gesture to underline relations which have been developing over the recent years and to express my wish that our friendly ties flourish even more during this new era," Bartholomew told private NTV television in Istanbul before his departure. "I am very hopeful in this matter."
In a sign of common bonds between East and West, the Vatican said the Gospel during the installation Mass at St. Peter's Square will be chanted in Greek instead of Latin, the language used for many other elements of the ceremony.
The Eastern and Western churches were united until the Great Schism of 1054, a divide precipitated largely by disagreements over the primacy of the pope. Francis' predecessor, the now retired Benedict, made a priority of uniting all Christians, and a joint committee has worked to mend the rift.
Rev. Dositheos Anagnostopoulos, the spokesman for the Istanbul-based Patriarchate, said Bartholomew would be the first Orthodox spiritual leader to attend an investiture since the Schism. The decision was "the fruit" of the growing dialogue between the Roman Catholic and Orthodox churches, he said.
Bartholomew went further: "Even before the churches were divided in 1054, a patriarch from Istanbul did not attend the inauguration," he explained. But he said Francis is bringing out the best in people. "From the first day, he has won over hearts with his modest demeanor," the patriarch said. "I felt the wish to go and I am going willingly."