Concerning Marian Devotion
From The Anglican Service Book of 1991
Popular devotion to the Blessed Virgin Mary is an affirmation of the inseparable union between our Lord's true humanity and his full divinity. The Church teaches that he who was incarnate of the Holy Ghost and the Virgin Mary is a union of divine and human natures in one divine Person. That being the case, it is appropriate to call His Mother Theotokos (accurately rendered as "Birth-giver of God," but more usually translated as "Mother of God"). Indeed, the Nestorian controversy during the fifth century was ignited by the condemnation by the heretical Bishop of Constantinople of the use of the term Theotokos. Every orthodox doctrine about Mary is Christological, continuing the pattern of the Wedding Feast at Cana, where she says to the servants, "Whatsoever he saith unto you, do it." Because of her faith in the works of God, all generations have indeed "called her Blessed." Mary is the model of humanity redeemed by Christ, and the principal type of the Church.
The councils of the undivided Church encourage the faithful to venerate and emulate the saints of the Christian family, and this is supremely true of the Blessed Virgin Mary. Adoration, however, is due only to the Holy Trinity and devotion to the saints is supplementary to the worship of the one, true, living God. It is an expression of the unity of the whole family of God in Heaven and on earth. At the heart of all Marian devotion is the simple request for the prayers of our Mother in Christ - one who is held by the common tradition of the Church to be "higher than the Cherubim, more glorious than the Seraphim," yet still a creature, and subordinate to God the creator.