Cathy Lynn Grossman, USA TODAY
To the sound of silver trumpets, Pope Benedict XVI entered St. Peter's Basilica Monday to celebrate Christmas Eve Mass and call for all people to make room for God in their heart.
As he did in 2011, the pope, now 85, bent and waving slowly, arrived on a red rolling platform to negotiate the football-field length main nave of St. Peter's.
Though his voice sounded thin, Benedict never hesitated as he led the prayers of the Christmas vigil to welcome the birth of the Christian savior.
Thousands more watched the Mass on jumbo screens in St. Peter's Square. Cameras turned discreetly away to the choirs or the magnificent church when he had to negotiate steps to the altar.
However soft his voice, Benedict's homily was a firm call for the world to open the door to God. He began with the Gospel lines about how Mary and Joseph could find no room In Bethlehem.
"Even if he seems to knock at the door of our thinking," said Benedict, he is often "made superfluous" in our thoughts, feelings and desires. "We are so full of ourselves that there is no room left for God" or the poor or the stranger.
Benedict called for prayer for "all who live and suffer in all the places where Christ lived," naming the Israelis and Palestinians, Lebanon, Iraq and Syria.
He acknowledged that in history, people acting as if "God were their private property" have been violent, arrogant and intolerant in God's name, but religion is not at fault for violence in this world.
"It is not true that denial of God would lead to peace. If God's light is extinguished, then human dignity is extinguished," he said. The birth of the Christ child introduces God's word to the world. "Christ is our peace and he proclaimed peace..."
Two hours later, the pope gave his final benediction and, accompanied by a contingent of children bearing flowers, moved to a side altar where the figure of the Christ child was placed in a creche. A shy smile lit his face as he rode the platform back down the aisle.
Shortly before the Christmas Eve Mass, the Vatican released the theme of the message Pope Benedict for the World Day of Peace: "Blessed are the peacemakers."
Earlier in the afternoon, Benedict ushered in the start of the Christmas Eve celebrations by witnessing the ceremonial opening of the creche in the square and lighting a Christmas candle in the window of his apartment.
An assistant held the match and steadied the glass-enclosed candle and then the pope blessed the crowd below, which had gathered for the unveiling of a Nativity scene in St. Peter's Square.
Christmas season is an exhausting run for the 85-year old Benedict - the sixth-oldest pope since the 15th century.
He had a few hours for a family dinner with his brother, the Rev. Georg Ratzinger, at the papal apartments before the evening Mass, according to Reuters.
Christmas Day is his annual blessing Urbi et Orbi, (to the city and the world) and his Christmas message. On New Year's Eve there are prayers to thank God for his goodness in the passing year.
Then New Year's Day he celebrates a special Mass and offers a prayer for world peace. That's when a global audience tunes in to the Vatican to see him lead the world's 1.2 billion Catholics in prayer and celebration.
Concern about his health ramped up this fall when he surprised the world by appointing six new Cardinals, princes of the church who will one day elect his successor. Most Vatican-watchers expected it would be 2013 before more names were added to the College of Cardinals.
As Cardinal Joseph Ratzinger, he suffered a stroke while vacationing in the Alps which briefly affected his eyesight and weakened his heart. The Vatican said he suffered another mild stroke in May 2005 after being elected pope.
While the pope conserves his physical strength, he has put new energy into making strategic use of modern media outreach.
More than 2.2 million people - 1.3 million in English - now follow Benedict's personal Twitter account in eight languages. So far there have been 12 tweets - answering questions posed to him or drawing 140-characters of inspiration from his addresses.
He wrote about concern for global poverty in an opinion piece for the British paper, the Financial Times, last week.
The pope caused a minor media stir earlier this year over the third book in his best-selling series, Jesus of Nazareth. Critics zeroed in on fine points in The Infancy Narratives, such as whether the angels spoke or sang at the news of Christ's birth.
Benedict writes that, "speech of angels is actually song, in which all the glory of the great joy that they proclaim becomes tangibly present." This puts the pope's stamp on the real presence of angels but not necessarily on the other well-known faces in the Christmas tableau - the Magi (the three kings).
For those who celebrate Jan. 6, when Christians say the Magi reached Bethlehem with their gifts, Benedict calls them historical events with theological relevance, says, Mark Brumley, CEO of Ignatius Press, which publishes Benedict 's writings in English.
But Benedict's defense of historical validity of the Christmas story in the Gospels is less important than his theology-for-the-common-Christian approach, says John Allen, Vatican expert for the National Catholic Reporter and author of a biography of Benedict.
Allen quotes the pope in pointing out his chief aim is "to help people on their path toward and alongside Jesus."
The Nativity scene in St. Peter's Square has already made headlines -- but not for religious reasons. It was donated to the Vatican after embarrassing leaked documents pointed out that the Holy See spent $717,000 for last year's creche.
The 2012 creche, an elaborate miniature recreation of Bethlehem with tiny characters looking toward the glowing manger scene, was paid for with corporate and private donors who raised $110,000. The Vatican kicked in nearly $24,000 for labor and set-up costs.
Last week, the pope pardoned his former butler who gave stolen documents about Vatican finances to an Italian journalist.