Saint Leo the Great says,
For the birth of Christ is the source of life for Christian folk, and the birthday of the Head is the birthday of the body. Although every individual that is called has his own order, and all the sons of the Church are separated from one another by intervals of time, yet as the entire body of the faithful being born in the font of baptism is crucified with Christ in His passion, raised again in His resurrection, andplaced at the Father's right hand in His ascension, so with Him are they born in this nativity. For any believer in whatever part of the world that is re-born in Christ, quits the old paths of his original nature and passes into a new man by being re-born; and no longer is he reckoned of his earthly father's stock but among the seed of the Saviour, Who became the Son of the man in order that we might have the power to be the sons of God....It is through the Spirit that we know of things spiritual. This gift Jesus sent to us from the Father. Through the Holy Spirit we are lifted above all the concerns of this earthly world. It is only in this way we can find true peace. Our challenge is to find our own peace with God. This is the nature of the preparation we should be making during this Nativity season. Then, when the glorious day comes on December 25th, we can truly celebrate and glorify Him with peace.
More from Saint Leo the Great,
The Saviour then, dearly beloved, is born not of fleshly seed but of the Holy Spirit, in such wise that the condemnation of the first transgression did not touch Him. For, as the blessed Apostle teaches, "we have received not the spirit of the world but the Spirit which is of God, that we may know the things which are given us by God." The Apostle says "being justified therefore by faith let us have peace towards God." The mystery of this boon is great, dearly beloved, and this gift exceeds all gifts that God should call man son, and man should name God Father: for by these terms we perceive and learn the love which reached so great a height. If it is gain the praise of men that the father's glory should shine again in their descendants, how much more glorious is it for those who are born of God to regain the brightness of their Maker's likeness and display in themselves Him Who begat them, as the Lord says: "Let your light so shine before men that they may see your good works and glorify your Father who is in heaven?" We know indeed, as the Apostle John says that "the whole world lies in the evil one," and by the deception of the Devil and his angels numberless attempts are made either to frighten man in his struggle upwards by adversity or to spoil him by prosperity, "but greater is He that is in us, than he that is against us," and they who have peace with God and are always saying to the Father with their whole hearts "thy will be done" can be overcome in no battles, can be hurt by no assaults.
Secure a peace with God that nothing can destroy, by accepting His gracious service, in order that we may not only surrender ourselves in obedience to our King but also be united to Him by our free-will....
This is the aim of the preparatory season that seems so distorted in commercial madness. We must not allow ourselves to be distracted from the real purpose of this preparatory time.
Reference: Saint Leo the Great Sermon 22
More on the Nativity
More on the Nativity