Speaking at a Rome homeless shelter, Pope Francis has said the humility of Jesus Christ's birth shows that mankind can find God in poverty.

The Pope was at the shelter to open a special Holy Door for the homeless during the Year of Mercy.

"This is the door of the Lord," the Pope said Dec. 18 as he opened the Holy Door. "Open the gates of justice. For your great mercy will enter into your house, O Lord."

The Pope then paused in prayer and proceeded in to celebrate Mass at the homeless shelter in Rome's Termini – John Paul II train station. About 200 people were in the congregation, representing all the Caritas centers in Rome.

In his impromptu homily, the Pope stressed that Jesus was not born to a princess in a palace. Rather, he came in humility to a simple young girl who lived on the outskirts of the Roman Empire.

There is a lesson here on where to find God, Pope Francis said.

"If you want to find God, look him for humility, look for him in poverty. Seek him where he is hidden: in the most needy, the sick, the hungry, the imprisoned," he said, according to Vatican Radio.

"This is not luxury, this is not the way of great wealth, this is not is the way of power. This is the way of humility," he continued.

"Today we pray for Rome, for all the inhabitants of Rome, for everyone, starting with me, because the Lord give us the grace to feel ourselves rejected, because we do not have any merit: only he gives us mercy and grace," he said. "To get closer to that grace, we must approach the rejected, the poor, to those who need it most."

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He also voiced his desire for a spiritual renewal at Christmas.

"This Christmas I wish that the Lord is born in the heart of each of us, hidden so that no one realizes," Pope Francis said.

The homeless shelter is named for the 20th century Italian priest Don Luigi di Liegro, who founded the Rome diocese's Caritas organization.

The Catholic Church's Jubilee Year of Mercy began Dec. 8. Pope Francis declared the event to help encourage acts of faith, charity, and mercy.

The Holy Doors of the Rome diocese are only opened during jubilee years so that pilgrims can enter through them in order to gain the plenary indulgence that is connected with the jubilee.

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Four Holy Doors have been opened in the Rome diocese, including the homeless shelter's door. Pope Francis opened the Holy Doors at St. Peter's Basilica and the Archbasilica of St. John Lateran. American Cardinal James Harvey opened the Holy Door at St. Paul's Outside-the-Walls. On Jan. 1 Pope Francis will open the Holy Door at St. Mary Major Basilica.

The Pope has asked the Catholic bishops of the world to designate Holy Doors at churches in their dioceses.