Saint Leo the Great teaches, “Today, dearly beloved, our Savior is born: let us rejoice! Surely there is no place for mourning on the birthday of true Life itself, who has swallowed up mortality with all its fear, and brought us the joyful promise of life everlasting. No one is excluded from taking part in our jubilation. All have the same cause for gladness, for as our blessed Lord, slayer of sin and death, found none free from guilt, so has he come to set us all alike at liberty.
Let the saint exult, since he is soon to receive recompense; let the sinner give praise, since he is welcomed to forgiveness; let the unbeliever take courage, since he is called unto life. For in the fullness of time ordained by the inscrutable mystery of the divine decree, the Son of God clothed himself with the nature of that human race which he was to reconcile to its Maker. Thus would he vanquish the devil, the author of death, through that very nature which had once yielded him the victory.”