Orthodoxy is the correct veneration of the Most Pure and Most Holy Virgin Mary, the Theotokos, who, with the assembly of the prophets, apostles, martyrs and all the saints, is our unsleeping mediatress before God. In regard to the veneration of the Mother of God, the Roman Catholic Church likewise diverges greatly from the ancient ecclesiastical Orthodox teaching. We have in mind the Catholic teaching known as the dogma of the "Immaculate Conception of the Mother of God."
In the official enactment of the Roman throne concerning this dogma, it is said: "The Most Blessed Virgin Mary, in the first moment of her conception, by a special grace of the omnipotent God and by a special privilege, for the sake of the future merits of Jesus Christ, the Saviour of the human race, was preserved free of all stain of original guilt" (Bull of Pope Pius IX on the new dogma, 1854). In other words, the Mother of God, at her conception, by a special act of Divine Providence, was freed from original sin, which by inheritance from our forefather has spread to all mankind.
The first Christian millennium did not know such a teaching. Beginning with the twelfth century, that is, already after the falling away of the Western church from the Universal Church, the idea of the Immaculate Conception began to spread among the clergy and laity. The new teaching provoked a multitude of disputes. Renowned theologians of the West, such as Thomas Aquinas, Bernard of Clairvaux and others rejected it.
The Orthodox Church acknowledges the birth of the Mother of God as holy, immaculate and blessed in the sense that this birth was from aged parents, that it was announced by an angel of God, that it served for the salvation of mankind, but it occurred within the usual laws of human life, both in a spiritual and physical regard. The Mother of God is also dear to us because she has the same nature as we all have; but she, by the ascetic struggle of her life, beginning from childhood, vanquished in herself her sinful nature and ascended on high as more honorable than the Cherubim and incomparably more glorious than the Seraphim. But if a different spiritual nature were given to her, apart from her will, then she is no longer ours and cannot constitute our glory. We cannot then say to God: "We have given her to Thee," as the Church says concerning this on the feast of Christ's Nativity.
Catholics, ostensibly desiring to magnify the Mother of God, separate her from mankind and ascribe to her different spiritual nature. The Roman Catholic dogma of the Immaculate Conception does not elevate, but demeans the Mother of God, since, if she were born free of sin and holy, then in the attainment of holiness there is no merit of her own. This dogma demeans also the work of men's redemption by Christ's death, since it allows the possibility - even though for only one person - to attain holiness apart from this redemption.