By David Willey
BBC News, Rome
The Pope continued the tradition of his predecessor
Pope Benedict XVI has delivered his traditional Christmas message and blessing in Rome from the balcony of St Peter's Basilica, offering a personal vision of how to tackle the world's ills.
He called on the men and women of the 21st Century to take inspiration from the infant Christ child lying in the manger to gather the necessary courage and build a new world order based on just ethical and economic relationships.
A united human family, the Pope said, will better be able to confront the problems of our times.
Benedict XVI catalogued the main problems that humanity faces today: first the threat of terrorism, then the humiliating poverty in which millions of people now live, then the proliferation of weapons and finally pandemics and environmental destruction.
In front of the Pope rose a 30m-high fir tree decorated with Christmas lights, sent as a gift to him from Austria.
Nearby was the largest nativity scene ever seen at the Vatican with larger-than-life-size figures representing the scene at Christ's birth in Bethlehem.
For centuries the Roman Catholic Church has celebrated Christmas by creating cribs inside churches, and encouraging believers to create images of the nativity scene in their own homes.
Thousands of pilgrims and tourists packed St Peter's Square to hear the Pope speak.
Millions more were watching him on television or listening to him on the radio in a worldwide hook-up.
Rain and cold weather did not deter the crowds who paraded a huge variety of coloured umbrellas.
"In the millennium just past, and especially in the last centuries, immense progress was made in the areas of technology and science," Pope Benedict said.
"Today we can dispose of vast material resources. But the men and women in our technological age risk becoming victims of their own intellectual and technical achievements, ending up in spiritual barrenness and emptiness of heart.
"That is why it is so important for us to open our minds and hearts to the Birth of Christ, this event of salvation which can give new hope to the life of each human being," he said.
"The modern age is often seen as an awakening of reason from its slumbers, humanity's enlightenment after an age of darkness. Yet without the light of Christ, the light of reason is not sufficient to enlighten humanity and the world," the Pope concluded.
After giving his blessing the Pope offered his Christmas greetings in over 30 different languages, following a custom established by his predecessor the late Pope John Paul II.
They included Chinese, Russian, Arabic and Swahili, tongues familiar to few in his audience, yet an indication of the worldwide reach of his 1.1 billion-strong Church.