In his Christmas Eve homily on Thursday (local time), Pope Francis denounced what he called society's obsession with consumerism, pleasure, abundance and wealth, as he talked about the simplicity of Jesus' birth.
Christians around the world are remembering the birth of Jesus. But in his only public Christmas Mass at St Peter's Basilica, the Pope rebuked a "culture of indifference, which not infrequently turns ruthless".
He said Jesus "calls us to act soberly, in other words, in a way that is simple, balanced, consistent, capable of seeing and doing what is essential".
Pope Francis recalled Jesus' birth in a Bethlehem stable, saying the boy was "born into the poverty of this world; there was no room in the inn for him and his family".
"In a world which all too often is merciless to the sinner and lenient to the sin, we need to cultivate a strong sense of justice," he said.
On Friday, tens of thousands are expected at St Peter's Square for the traditional Christmas Day speech, which has historically been used to address violence and injustice across the world.