By Philip Pullella
VATICAN CITY (Reuters) - Pope John Paul led Roman Catholics into Christmas on Thursday, calling on a world caught up in conflict to open itself to the peace of the infant Jesus.
"Too much blood is still being shed on earth," the 83-year-old pontiff said in the homily of a Christmas midnight mass in St Peter's Basilica that once again tested his strength.
The mass from Christendom's largest church, marking the Polish pope's 26th Christmas as leader of the world's one billion Catholics, was broadcast live to nearly 50 countries.
"Too much violence and too many conflicts trouble the peaceful coexistence of nations," he said, speaking slowly in Italian and reading his homily in a relatively clear voice.
"You come to bring us peace. You are our peace," he said in a homily that was mostly of religious content, recalling the birth of Jesus in Bethlehem.
"May the radiance of your birth light up the night of world. May the power of your message of love thwart the proud snare of the evil one. May the gift of your life make us understand ever more clearly the worth of the life of each human being," he said.
As the voices of the Sistine Chapel choir filled the basilica with singing, the pope, resplendent in gold and white vestments, was wheeled up the center aisle of the basilica to applause.
His Parkinson's disease makes it difficult to talk, and leg and hip ailments make it nearly impossible for him to walk or stand.
He celebrated the mass sitting on a special chair that rises to allow him to reach the altar without standing.
Aides said he insisted on celebrating the mass himself on the second-most holy day of the Christian liturgical calendar after Easter.
In recent months the pope, who marked his 25th anniversary in October, has been attending ceremonies but delegating a senior cardinal to celebrate the services in order to conserve his strength.
For the first time since his election in 1978, the pope is celebrating Christmas with no firm plans for travel in the following year, although there have been some invitations.
The highlight of the Christmas season will come later on Thursday when the pope delivers his "Urbi et Orbi" (to the city and the world) message and blessing from the central balcony of St Peter's Square to the crowds in the square below.
He traditionally reads Christmas greetings in many languages just after the twice-yearly Urbi et Orbi address.