Under the majestic dome of St. Peter's basilica, thousands gathered on Christmas Eve to watch the pope's first Christmas mass.

Pope Francis chose his message of hope from the book of Isaiah.

"The people who walked in darkness have seen a great light," he said.

"In this night, as the spirit of darkness enfolds the world, there takes place anew the event which always amazes and surprises us: the people who walk see a great light. A light which makes us reflect on this mystery: the mystery of walking and seeing," Pope Francis said.

"In our personal history too, there are both bright and dark moments, lights and shadows," he said. "If we love God and our brothers and sisters, we walk in the light; but if our heart is closed, if we are dominated by pride, deceit, self-seeking, then darkness falls within us and around us."

Francis Monday visited his predecessor Pope Benedict the 16 th, wishing him a "Merry Christmas" and praying together.

It was another extraordinary image from a man who has captivated the world with simple acts of kindness and humility. Earlier this year, he welcomed the little boy who hugged him and wouldn't leave his side, embraced a disfigured man and even posed for selfies with tourists.

This week, Francis reminded the faithful that this season is about so much more than parties and presents.

"Christmas celebrations are often full of sound," he tweeted. "It would be good for us to make room for silence, to hear the voice of Love."