Pope Benedict has told worshippers at an Easter mass that technological progress in the absence of awareness of God and moral values poses a threat to the world.
The pontiff presided at an Easter vigil Mass in St Peter's Basilica to usher the 1.2 billion-member church into the most important day of its liturgical calendar.
The basilica was in the dark for the start of the service to signify the darkness in Jesus' tomb before what Christians believe was his resurrection from the dead three days after his crucifixion.
Some 10,000 faithful in the basilica lit candles as the pope moved up the central aisle on a wheeled platform he uses to conserve his strength.
The basilica's lights were turned on when he reached the main altar.
Wearing gold and white vestments at the Mass, his last Holy Week service before Easter Sunday, Pope Benedict wove his sermon around the theme of darkness and light.
"The darkness enshrouding God and obscuring values is the real threat to our existence and to the world in general," he said.
Benedict, repeating one of the central themes of his pontificate, said man was too often in awe of technology instead of being in awe of God.
"If God and moral values, the difference between good and evil, remain in darkness, then all other 'lights', that put such incredible technical feats within our reach, are not only progress but also dangers that put us and the world at risk," he said.
"With regard to material things, our knowledge and our technical accomplishments are legion, but what reaches beyond, the things of God and the question of good, we can no longer identify," he said.
The 84-year-old pope, who returned from a gruelling trip to Mexico and Cuba last week, looked fatigued at the long service, during which be baptised eight adults from Italy, the United States, Slovakia, Turkmenistan, Albania, Germany and Cameroon.
On Sunday the pope will preside at an Easter day Mass and then deliver his twice-yearly "Urbi et Orbi" (to the city and the world) blessing and message from the central balcony of St Peter's Basilica.