If therefore there was ever a good reason to rejoice over the birth
of any child, it must surely be today on the birthday of Jesus, the Son of Mary, Who alone of all men is called and truly is God with us—of Whom alone it can be said that the Word was made flesh and dwelt among us. Christmas Day is nothing if not a day of universal joy.
Children should rejoice because on this day God Himself became as
one of them; virgins, because a Virgin brought forth and remained unstained even after giving birth; wives, because one of their number became the Mother of God; sinners, because their Mediator and Savior and Healer has come to redeem them; the just, because their Reward exceeding great has been born into the world. In fine, all faithful Christians should rejoice that their Creator and Lord has taken on human flesh and begun His reign over the hearts of men, not only as God, but also as the Son of Man among the children of men.
Were we not to celebrate the feast of Christmas as joyfully and as
solemnly as we should, we would be worse than unbelieving pagans, who for all their sins at least were not wanting in due respect for the birthdays of the great ones who lorded over them. Do I say worse than infidels? Worse than the beasts of the field who cannot show their appreciation of God’s becoming man because they do not know Him. But we know Him and know what His
coming in our flesh has meant to us.
If you do not believe me, believe the Catholic Church which for so
many centuries has gone to the limit of propriety in exulting over the
birth of her Redeemer. If you will not even believe the Church, at least listen to the angel who was sent from heaven to announce the tidings of great joy which shall be to all the people, believers and pagans, Jews and Gentiles—to all without exception.
-St. Peter Canisius