From a sermon by Saint Leo the Great:
“Dearly beloved, today our Savior is born; let us rejoice. Sadness should have no place on the birthday of life. The fear of death has been swallowed up; life brings us joy with the promise of eternal happiness.
No one is shut out from this joy; all share the same reason for rejoicing. Our Lord, victor over sin and death, finding no man free from sin, came to free us all. Let the saint rejoice as he sees the palm of victory at hand. Let the sinner be glad as he receives the offer of forgiveness. Let the pagan take courage as he is summoned to life….
And so at the birth of our Lord the angels sing in joy: Glory to God in the highest, and they proclaim peace to his people on earth as they see the heavenly Jerusalem being built from all nations of the world. When the angels on high are so exultant at this marvelous work of God’s goodness, what joy should it not bring to the lowly hearts of men?….
Christians, remember your dignity, and now that you share in God’s own nature, do not return by sin to your former base condition. Bear in mind who is your head and of whose body you are a member. Do not forget that you have been rescued from the power of darkness and brought into the light of God’s kingdom.”