Catechism of the Catholic Church

525 Jesus was born in a humble stable, into a poor family. ²⁰² Simple shepherds were the first witnesses to this event. In this poverty heaven's glory was made manifest. ²⁰³ The Church never tires of singing the glory of this night:

The Virgin today brings into the world the Eternal
And the earth offers a cave to the Inaccessible.
The angels and shepherds praise him
And the magi advance with the star,
For you are born for us, Little Child, God eternal! ²⁰⁴

526 To become a child in relation to God is the condition for entering the kingdom. ²⁰⁵ For this, we must humble ourselves and become little. Even more: to become "children of God" we must be "born from above" or "born of God". ²⁰⁶ Only when Christ is formed in us will the mystery of Christmas be fulfilled in us. ²⁰⁷ Christmas is the mystery of this "marvellous exchange":

O marvellous exchange! Man's Creator has become man, born of the Virgin. We have been made sharers in the divinity of Christ who humbled himself to share our humanity. ²⁰⁸