Benedict appeared tired by the end of the Mass, and a dry cough interrupted his homily.
In his homily, Benedict lamented that Christmas has become an increasingly commercial celebration that obscures the simplicity of the message of Christ's birth.
"Let us ask the Lord to help us see through the superficial glitter of this season, and to discover behind it the child in the stable in Bethlehem, so as to find true joy and true light," he said.
It was the second time in two days that Benedict has pointed to the need to rediscover faith to confront the problems facing the world. In his end-of-year meeting Thursday with Vatican officials, Benedict said Europe's financial crisis was largely "based on the ethical crisis looming over the Old Continent."
Benedict officially launched Christmas a few hours before the evening Mass, lighting a candle in his studio window overlooking St. Peter's Square in a sign of peace, as crowds gathered to witness the unveiling of the Vatican's larger-than-life nativity scene.
Security was tight for the evening Mass, as it has been in recent years. There were no repeats of the 2008 and 2009 Christmas Eve security breaches, in which a woman with a history of psychiatric problems jumped the security barrier along the basilica's central aisle and lunged for the pope.
On Sunday, Benedict will deliver his traditional "Urbi et Orbi" speech - Latin for "to the city and the world" - from the central loggia of St. Peter's overlooking the piazza. Usually, the speech is a survey of sorts of the hardships and wars confronting humanity. He is also due to deliver Christmas greetings in dozens of languages.
Next weekend, he will preside over a New Year's Eve vespers service, followed by a New Year's Day Mass. A few days later he will celebrate Epiphany Mass, followed by his traditional baptizing of babies in the Vatican's frescoed Sistine Chapel.
