The Holy Church established this feast during the first centuries of the Christian Faith.
The event that we celebrate—the birth of the God-Chosen maiden—brought joy to all the world, for the God-man, Jesus Christ, Who shone forth from Her, destroyed God’s curse which weighed heavily upon the transgressing and accursed human race, and brought God’s blessing upon it; having trampled down inherent death, He gave people eternal life.
[...] What joy does the Nativity of the Mother of God bring us? Let us explain in more detail the Church hymn which explains the meaning of this feast’s joy.
Through the birth of the Ever-Virgin, through Her only-begotten Son and God, cursed and outcast mankind makes peace with God Who is immeasurably offended by man’s sins, for Christ became the mediator of this peace (cf. Rom. 5:10-11).
Man is freed from the curse and eternal death, made worthy of the blessing of the Heavenly Father.
He is united and co-mingled with the Divine nature; he is raised to his first inheritance by this co-mingling, according to the Church hymn.
Mankind, once an outcast, has been made worthy of sonship to the Heavenly Father, received the promise of the glorious resurrection and eternal life in the heavens together with the angels.
This has all been and is being wrought by the Son of God incarnate from the Most Pure Virgin from the Holy Spirit, and by the intercession of His Most Pure Mother.
How honored and magnified is mankind through the Holy Virgin Mother of God, for it has been made worthy of renewal and sonship by God.
She Herself was made worthy by Her immeasurable humility and exceedingly great purity and holiness to be the Mother of the God-man!
She is ever the most powerful Intercessor for the Christian race before Her Son and God!
She is our Hope unashamed. She turns away from us the dark cloud of God’s righteous wrath, opens to us the ancient paradise by Her powerful intercessions.
She upholds the thrones of kings, and preserves them unshakeable to the ages.
[...] She is the Surety of Sinners for salvation. To Her do Christians direct their numberless prayers, requests, and praises, doxologies and thanksgiving.
She has worked and continues to work miracles without number in the Church, to the ends of the world.
Let us brightly celebrate the feast of the Nativity of the Most Pure Virgin Mary, adorning ourselves with all the Christian virtues.
John of Kronstadt (1829-1908; Russian Orthodox): Homily on the Day of the Nativity of the Most Holy Mother of God @ Pravoslavie.