Pope Benedict XVI arrives for a meeting of religious leaders at St Mary's University College Chapel at Twickenham in west London September 17, 2010. The Pope is on a four-day visit to Britain and Scotland. REUTERS/Max Rossi (BRITAIN - Tags: RELIGION POLITICS) 

Pope Benedict XVI releases a dove from a window of his private apartments as he leads the Angelus prayer in Saint Peter's Square at the Vatican January 30, 2011. REUTERS/Max Rossi (VATICAN - Tags: RELIGION) 

Pope Francis (R) greets Emeritus Pope Benedict XVI before a mass in Saint Peter's square at the Vatican September 28, 2014. Former Pope Benedict will take part in a gathering of elderly people at the Vatican on Sunday, only his third appearance at a public event since he resigned in February 2013. REUTERS/Tony Gentile (VATICAN - Tags: RELIGION TPX IMAGES OF THE DAY) 

Pope Benedict XVI waves to worshipers as he leaves a Mass at Yankee Stadium in New York, April 20, 2008. REUTERS/Mike Segar (UNITED STATES) 

Pope Benedict XVI enters a building during his visit to Lambeth Palace in London, Britain, September 17, 2010. Picture taken September 17, 2010. REUTERS/Stefan Wermuth/File Photo SEARCH "POY DECADE" FOR THIS STORY. SEARCH "REUTERS POY" FOR ALL BEST OF 2019 PACKAGES. TPX IMAGES OF THE DAY. 

Pope Benedict XVI celebrates the First Vespers and Te Deum prayers in Saint Peter's Basilica at the Vatican December 31, 2009. REUTERS/Alessia Pierdomenico (VATICAN - Tags: RELIGION IMAGES OF THE DAY) 

Pope Benedict XVI waves as he arrives for the Immaculate Conception celebration prayer in Piazza di Spagna (Spain's Square) in downtown Rome December 8, 2011. REUTERS/Alessandro Bianchi (ITALY - Tags: RELIGION TPX IMAGES OF THE DAY) 

Pope Benedict XVI leaves at the end of his weekly general audience in St. Peter's Square at the Vatican May 19, 2010. REUTERS/Alessandro Bianchi (VATICAN - Tags: RELIGION) 

Pope Benedict XVI replaces his zucchetto as he stands with Britain's Queen Elizabeth at the Palace of Holyroodhouse in Edinburgh, Scotland September 16, 2010. Pope Benedict arrived in Britain on Thursday hoping to win over one of Europe's most secular countries, but a last minute diplomatic hiccup and the possibility of a low turnout threaten the success of the visit. REUTERS/Dave ThompsonPool (BRITAIN - Tags: POLITICS SOCIETY PROFILE RELIGION ROYALS) 

Pope Benedict XVI blesses the faithful as he leads his Urbi et Orbi (to the city and the world) Christmas Day message from the central balcony of Saint Peter's Square at the Vatican December 25, 2009. REUTERS/Alessandro Bianchi (VATICAN - Tags: RELIGION IMAGES OF THE DAY) 

Pope Benedict XVI smiles as he celebrates midnight mass in St. Peter's Basilica at the Vatican December 25, 2006. REUTERS/Alessandro Bianchi (VATICAN) 

Pope Benedict XVI prays while holding a candle light as he arrives to lead a vigil mass during Easter celebrations at the St. Peter's Basilica in the Vatican April 7, 2012.
REUTERS/Alessandro Bianchi (VATICAN - Tags: RELIGION) 

Pope Benedict XVI, Cardinal Joseph Ratzinger of Germany, waves from a balcony of St. Peter's Basilica in the Vatican. Pope Benedict XVI, Cardinal Joseph Ratzinger of Germany, waves from a balcony of St. Peter's Basilica in the Vatican after being elected by the conclave of cardinals, April 19, 2005. A new pope was elected by Roman Catholic cardinals on Tuesday to succeed John Paul II. The election of the 265th pontiff on only the second day of a conclave in the Vatican's frescoed Sistine Chapel was signaled by white smoke from the chapel chimney and the tolling of the bells of St. Peter's Basilica. REUTERS/Max Rossi 

Pope Benedict XVI looks on next to a young member of "Azione Cattolica" (Catholic Action movement) as a dove is released from a window of his private apartments as he leads the Angelus prayer in Saint Peter's Square at the Vatican January 29, 2012. REUTERS/Alessandro Bianchi (VATICAN - Tags: RELIGION TPX IMAGES OF THE DAY) 

Pope Benedict XVI reads a speech during a welcoming ceremony at Malta International airport April 17, 2010. Pope Benedict, starting a trip to Malta overshadowed by the sexual abuse scandal sweeping Roman Catholicism, said on Saturday that the Church had been "wounded by our sins." REUTERS/Tony Gentile (MALTA - Tags: RELIGION POLITICS IMAGES OF THE DAY) 

U.S. President Barack Obama (R) and his wife Michelle Obama meet with Pope Benedict XVI (C) at the Vatican July 10, 2009. REUTERS/Jason Reed (VATICAN POLITICS RELIGION IMAGES OF THE DAY) 

Pope Benedict XVI places a note in the Western Wall, Judaism's holiest prayer site, in Jerusalem's Old City May 12, 2009. Pope Benedict visited holy sites in Jerusalem at the heart of the Israeli-Palestinian conflict on Tuesday as part of a pilgrimage beset by Jewish disappointment over his remarks on the Holocaust. REUTERS/David Silverman/Pool (JERUSALEM RELIGION POLITICS IMAGES OF THE DAY) 

A gust of wind blows Pope Benedict XVI's skullcap as he arrives to lead his general audience in Saint Peter's Square at the Vatican September 5, 2007. REUTERS/Max Rossi (ITALY) 

A gust of wind blows Pope Benedict's mantle during his weekly Wednesday general audience in St. Peter's Square at the Vatican June 6, 2007. REUTERS/Tony Gentile (VATICAN) 

Pope Benedict XVI arrives for the canonization ceremony of Italian nun Rosa Venerini, Mexican bishop Rafael Guizar, Italian priest Filippo Smaldone and Indiana nun Theodore Guerin in St. Peter's square at the Vatican, October 15, 2006. REUTERS/Giampiero Sposito (VATICAN) 

Pope Benedict XVI greets the youth in front of a huge Jesus Christ portrait in Krakow May 27, 2006. Pope Benedict paid an emotional visit to the birthplace of his predecessor John Paul on Saturday and told Poles he was praying that their favourite son would move swiftly towards Catholic sainthood. REUTERS/Wolfgang Rattay 

The last book of former Pope Benedict "The last conversations" in seen in a library in Rome, Italy, September 9, 2016. REUTERS/Max Rossi TPX IMAGES OF THE DAY

Pope Benedict XVI waves as he arrives to lead the weekly general audience in Saint Peter's Square at the Vatican April 18, 2012. REUTERS/Max Rossi (VATICAN - Tags: RELIGION TPX IMAGES OF THE DAY) 

Pope Francis (L) embraces Emeritus Pope Benedict XVI before opening the Holy Door to mark opening of the Catholic Holy Year, or Jubilee, in St. Peter's basilica, at the Vatican, December 8, 2015. REUTERS/Max Rossi TPX IMAGES OF THE DAY

Former Pope Benedict XVI arrives escorted by Archbishop Georg Ganswein (R) to attend the canonisation ceremony of Popes John XXIII and John Paul II to start in St. Peter's Square at the Vatican April 27, 2014. Pope John XXIII, who reigned from 1958 to 1963 and called the modernising Second Vatican Council, and Pope John Paul II, who reigned for nearly 27 years before his death in 2005 and whose trips around the world made him the most visible pope in history, will be declared saints by Pope Francis at an unprecedented twin canonisation on Sunday. REUTERS/Max Rossi (VATICAN - Tags: RELIGION TPX IMAGES OF THE DAY)

Pope Benedict XVI holds his last general audience in St Peter's Square at the Vatican February 27, 2013. The weekly event which would normally be held in a vast auditorium in winter, but has been moved outdoors to St. Peter's Square so more people can attend. The pope has two days left before he takes the historic step of becoming the first pontiff in some six centuries to step down instead of ruling for life. REUTERS/Alessandro Bianchi (VATICAN - Tags: RELIGION TPX IMAGES OF THE DAY)

Pope Benedict XVI waves from his Popemobile as he rides through a packed Saint Peter's Square at the Vatican during his last general audience, February 27, 2013. The weekly event which would normally be held in a vast auditorium in winter, but has been moved outdoors to St. Peter's Square so more people can attend. The pope has two days left before he takes the historic step of becoming the first pontiff in some six centuries to step down instead of ruling for life. REUTERS/Stefano Rellandini (VATICAN - Tags: RELIGION)

Pope Benedict XVI leaves at the end of his last Angelus prayer before stepping down in Saint Peter's Square at the Vatican February 24, 2013. Pope Benedict, speaking in his last Sunday address before becoming the first pope in some six centuries to step down, said he was following God's wishes and that he was not abandoning the Roman Catholic Church. REUTERS/Max Rossi (VATICAN - Tags: RELIGION) 

Pope Benedict XVI arrives to lead Ash Wednesday mass at the Vatican February 13, 2013. Thousands of people are expected to gather in the Vatican for Pope Benedict's Ash Wednesday mass, which is expected to be his last before leaving office at the end of February. REUTERS/ Alessandro Bianchi (VATICAN - Tags: RELIGION TPX IMAGES OF THE DAY) 

An empty papal throne is pictured before the Ash Wednesday mass at the St. Peter's Basilica in the Vatican February 13, 2013. Thousands of people are expected to gather in the Vatican for Pope Benedict's Ash Wednesday mass, which is expected to be his last before leaving office at the end of February. REUTERS/Alessandro Bianchi (VATICAN - Tags: RELIGION) 

Vatican spokesman Father Federico Lombardi talks to reporters during a news conference at the Vatican February 11, 2013. Pope Benedict has no specific illness and his decision to resign was taken with no outside pressure, the Vatican spokesman said on Monday after the pontiff's shock announcement that he would step down at the end of this month. REUTERS/Alessandro Bianchi (VATICAN - Tags: RELIGION) 

Leo Fischer, editor-in-chief of the German magazine "Titanic", poses for a picture in his office in Frankfurt July 11, 2012. The "Titanic", that angered the Vatican with a cover picture satirising Pope Benedict, said on Wednesday it hoped to defuse the dispute in "a spirit of Christian reconciliation". At the Vatican's request, a German court banned the magazine on Tuesday from publishing the images of the pope on the Internet and from further publication of the printed edition, though tens of thousands of copies are already in circulation. REUTERS/Alex Domanski (GERMANY - Tags: MEDIA RELIGION BUSINESS CRIME LAW TPX IMAGES OF THE DAY) 

Children dressed in traditional Bavarian costumes dance for Pope Benedict XVI during the Pontiff's 85th birthday celebrations in the Clementine Hall at the Vatican April 16, 2012. REUTERS/Gregorio Borgia/Pool (VATICAN - Tags: RELIGION SOCIETY TPX IMAGES OF THE DAY) 

Pope Benedict XVI answers to reporters' questions during a news conference aboard his flight to Mexico March 23, 2012. REUTERS/Tony Gentile (MEXICO - Tags: POLITICS RELIGION) 

A body guard (C) for Pope Benedict XVI deflects the hand of a woman reaching towards the pontiff as he leaves the Basilica in the city of Ouidah in Benin, November 19, 2011. Pope Benedict said on Saturday the developed world could not continue to look down on Africa "with the judgmental tone of a moralizer" and impose rules, but must come up with real partnership solutions to solve the continent's many problems. REUTERS/Finbarr O'Reilly (BENIN - Tags: RELIGION) 

The speech of Pope Benedict XVI to the German Bundestag, the lower house of parliament, is broadcast on a large screen at the Olympic Stadium in Berlin September 22, 2011. Pope Benedict urged the faithful not to leave the Roman Catholic Church on Thursday as he began a four-day visit to Germany, where record numbers have quit the pews in protest against clerical sex abuse of youths. About 100 left-wing deputies planned to boycott the pope's speech to the Bundestag, saying it violates the separation of church and state. REUTERS/Kai Pfaffenbach (GERMANY - Tags: RELIGION POLITICS) 

A gust of wind lifts Pope Benedict XVI's mantle during the weekly general audience at St. Peter's Square in the Vatican June 8, 2011. REUTERS/Max Rossi (VATICAN - Tags: RELIGION IMAGES OF THE DAY) 

Pope Benedict XVI holds his cross as he leads a solemn mass in Zagreb June 5, 2011. The Pope is on a two-day visit to Croatia. REUTERS/Alessandro Bianchi (CROATIA - Tags: RELIGION IMAGES OF THE DAY) 

New books about the Pope Benedict XVI are seen displayed inside a bookshop near the Vatican November 23, 2010. Pope Benedict says in the new book, called "Light of the World: The Pope, the Church, and the Sign of the Times", that he would not hesitate to become the first pontiff to resign willingly in more than 700 years if he felt himself no longer able, "physically, psychologically and spiritually", to lead the church. The book, an interview with German Catholic journalist Peter Seewald, has so far made headlines for the pope's cautious opening to the use of condoms to stop AIDS. REUTERS/Alessandro Bianchi (VATICAN - Tags: RELIGION MEDIA) 

Pope Benedict XVI leaves Oscott College seminary in Birmingham September 19, 2010. Pope Benedict told a Mass in England on Sunday the world felt "shame and horror" at suffering inflicted by his German homeland in World War Two and recalled a key air battle that saved Britain from Nazi invasion. REUTERS/Leon Neal/POOL (BRITAIN - Tags: RELIGION POLITICS EDUCATION) 

Pope Benedict XVI and Britain's Archbishop of Canterbury Rowan Williams (L) celebrate evening prayer at Westminster Abbey in London September 17, 2010. REUTERS/Richard Pohle/POOL (BRITAIN - Tags: RELIGION POLITICS) 

A bishop adjusts Pope Benedict XVI's mantle during the weekly Wednesday general audience in St. Peter's Square at the Vatican June 2, 2010. REUTERS/Tony Gentile (VATICAN - Tags: RELIGION IMAGES OF THE DAY) 

Pope Benedict XVI kisses a child as he leaves on his popemobile at the end of his weekly general audience in St. Peter's Square at the Vatican May 19, 2010. REUTERS/Alessandro Bianchi (VATICAN - Tags: RELIGION) 

Pope Benedict XVI prays inside St Paul's Grotto in Rabat, outside Valletta April 17, 2010. Roman Catholicism has been "wounded by our sins", Pope Benedict said at the start of a two-day visit to Malta, but he avoided directly referring to the sexual abuse scandals sweeping the world's largest Church. The pope visited the grotto where Saint Paul is believed to have stayed when he came to Malta in 60 A.D., converting the islanders to Christianity. REUTERS/Osservatore Romano (MALTA - Tags: RELIGION POLITICS IMAGES OF THE DAY) 

Pope Benedict XVI leads the Palm Sunday mass in Saint Peter's Square at the Vatican March 28, 2010. REUTERS/Alessandro Bianchi (VATICAN - Tags: RELIGION IMAGES OF THE DAY) 

Pope Benedict XVI kisses a young bagpipe player at the end of his weekly audience in the Paul VI hall at the Vatican December 23, 2009. REUTERS/Alessia Pierdomenico (VATICAN - Tags: RELIGION) 

Pope Benedict XVI delivers his weekly Angelus blessing to the crowd gathered below in Saint Peter's square at the Vatican November 29, 2009. REUTERS/Tony Gentile (VATICAN RELIGION) 

A gust of wind blows Pope Benedict XVI's mantle during a Wednesday general audience in Saint Peter's square at the Vatican October 21, 2009. REUTERS/Tony Gentile (VATICAN RELIGION IMAGES OF THE DAY) 

Pope Benedict XVI greets the crowd during his Angelus prayers in Romano Canavese, near Ivrea, northern Italy July 19, 2009. The Pope underwent minor surgery on July 17, 2009 after he slipped in the bath and broke his right wrist while on holiday in northern Italy. The Vatican said that the pope would have to wear a cast for about a month. REUTERS/Alessandro Garofalo (ITALY RELIGION IMAGES OF THE DAY) 

Pope Benedict XVI greets participants of the first European Meeting of University Students at the Vatican July 11, 2009. REUTERS/Osservatore Romano (VATICAN POLITICS RELIGION EDUCATION IMAGES OF THE DAY) 

EDITORIAL USE ONLY - NO COMMERCIAL OR BOOK SALES. Pope Benedict prays in the Golgotha, or Calvary, the traditional site where Jesus was crucified, in the Church of the Holy Sepulchre in Jerusalem's Old City May 15, 2009. Pope Benedict preached a message of hope for all mankind on Friday at one of the holiest sites in Christendom, telling his audience at the Church of the Holy Sepulchre in Jerusalem that "love is stronger than death". It was Benedict's first visit as pope to the place where Christ was crucified, died, was buried and then rose from the dead, according to the Christian faith. REUTERS/Yannis Behrakis (JERUSALEM RELIGION POLITICS IMAGES OF THE DAY) 

Pope Benedict XVI waves during a mass on Mount Precipice, where the Bible says a mob tried to hurl Jesus off a cliff, in the northern city of Nazareth May 14, 2009. Tens of thousands of the faithful turned out in the town of Jesus's boyhood on Thursday when Pope Benedict took his Holy Land pilgrimage to the heartland of Israel's minority Arab population. REUTERS/Tony Gentile (ISRAEL RELIGION POLITICS IMAGES OF THE DAY) 

Pope Benedict XVI waves as he rides in his Popemobile along the controversial Israeli barrier in the Aida refugee camp in the West Bank town of Bethlehem May 13, 2009. Pope Benedict spoke in the shadow of the fortified Israeli wall dividing Bethlehem from Jerusalem on Wednesday, calling it a tragic symbol of deadlock in the struggle for peace in the Middle East. REUTERS/Ammar Awad (WEST BANK RELIGION POLITICS CONFLICT) 

Pope Benedict XVI (R) visits the Western Wall, Judaism's holiest prayer site, in Jerusalem's Old City May 12, 2009. Pope Benedict visited holy sites in Jerusalem at the heart of the Israeli-Palestinian conflict on Tuesday as part of a pilgrimage beset by Jewish disappointment over his remarks on the Holocaust. REUTERS/Menahem Kahana/Pool (JERUSALEM RELIGION POLITICS) 

Pope Benedict XVI walks past Israel's national flag during a welcoming ceremony after his arrival at Tel Aviv's Ben Gurion International airport May 11, 2009. Pope Benedict on Monday began the most delicate part of his first trip to the Middle East, landing in Israel for a five-day tour that will take him to Jerusalem and the Palestinian territories. REUTERS/Tony Gentile (ISRAEL RELIGION POLITICS) 

A note written by Pope Benedict XVI during his visit at Yad Vashem Holocaust memorial in Jerusalem is seen in their guestbook May 11, 2009. Pope Benedict, on his first visit to Israel, said on Monday that the suffering of six million Jews murdered by Nazi Germany in the Holocaust must never be denied or forgotten. The note reads, "His mercies are not spent", the Book of Lamentations (3:22). REUTERS/Ronen Zvulun (JERUSALEM RELIGION POLITICS) 

Jordan's Prince Ghazi bin Muhammad bin Talal speaks to Pope Benedict XVI (L) during his visit to the King Hussein Bin Talal mosque in Amman May 9, 2009. Pope Benedict retraced the steps of Moses on Saturday, visiting the mountain where the Bible says the ancient prophet glimpsed the Promised Land before dying, and preached that religion helps man search for truth. REUTERS/Ahmed Jadallah (JORDAN RELIGION POLITICS) 

Pope Benedict XVI waves as leads his general audience in Saint Peter's Square at the Vatican May 6, 2009. Pope Benedict on Friday ventures into the political, cultural and religious minefield of the Middle East, starting a trip to Jordan, Israel and the Palestinian territories that will likely be his most difficult.Benedict will be carrying a lot of personal baggage as he starts the trip, which some Church observers see as another chance to mend fences with both Muslims and Jews after comments or actions perceived as insulting to them. REUTERS/Max Rossi (VATICAN RELIGION) 

Pope Benedict XVI arrives in the destroyed village of Onna, near Aquila, April 28, 2009. Pope Benedict XVI on Tuesday visited Onna and Aquila where some 40,000 people lost their homes in the 6.3 magnitude quake, which hit the Abruzzo region in the early hours of April 6, catching residents in their sleep. REUTERS/Max Rossi (ITALY DISASTER RELIGION SOCIETY IMAGES OF THE DAY) 

Franciscan Friars take pictures of Pope Benedict XVI as he leads an audience with Franciscan family at his summer residence of Castel Gandolfo, near Rome, April 18, 2009. REUTERS/Giampiero Sposito (ITALY RELIGION SOCIETY)