"The darkness enshrouding God and obscuring values is the real threat to our existence and to the world in general," the pope said.
"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," Benedict added.
The service began dramatically. Except for the twinkle of camera flashes, the basilica was almost pitch-black as the thousands of faithful in pews awaited Benedict's arrival through the rear entrance. After aides lit the candle, Benedict climbed aboard a raised platform that was wheeled up the long main aisle to the central altar. The wheeled device is used to save wear and tear on the pontiff, who turns 85 on April 16.
Benedict, who has made protection of the environment a theme of his papacy, made a reference to urban pollution in his homily. "Today we can illuminate our cities so brightly that the stars in the sky are no longer visible," he said. "Is this not an image of the problems caused by our version of enlightenment?"
"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," Benedict added, saying that faith was the "true enlightenment."
During the vigil ceremony, Benedict welcomed eight adult converts to the church, pouring water over their bowed heads in baptism.
In the Middle East, thousands of Christians gathered near Jerusalem's Church of the Holy Sepulcher for Easter Saturday and marched in processions brimming with tradition, taking turns to pray in the site where they believe Jesus was slain and buried.
"This day is very important for us. It's the waiting for the great celebration of the Resurrection," said the Rev. Ibrahim Shomali, a Palestinian Christian priest from the nearby town of Beit Jala.
They were led by Palestinian guards in black costumes richly embroidered with gold, topped with scarlet, rimless hats. They rhythmically pounded their staffs on the cobblestone ground, providing a beat for believers to march.
They were followed by Franciscan monks in plain brown robes, clerics in black garb, and then ordinary believers.
"This is the place where Jesus is in his tomb, this is the place, a magnet of the world," said worshiper Jim Carnie of New York. "The power of this place, to be here, it has to be experienced."
On Sunday morning, Benedict will lead Easter Mass in St. Peter's Square, then deliver a speech from the central balcony of the basilica.