What does the Bible say? “You are to conceive in your womb and bear a son, and you must name him Jesus. He will be great and will be called Son of the Most High. . . . And so the child will be holy and will be called Son of God.”—Italics ours; Luke 1:31-35, The New Jerusalem Bible.
That passage of Scripture clearly states that Mary was the mother of the “Son of God,” not of God himself. Could she have carried within her the One whom ‘the heavens themselves cannot contain’? (1 Kings 8:27) She never made such a claim. It is the teaching about the Trinity that has sown confusion over the identity of Mary. By proclaiming her Theotokos (a Greek word meaning “God-bearer”), or “Mother of God,” the Council of Ephesus, in 431 C.E., set the stage for Mary worship. The city of Ephesus where this church council was held had for centuries been at the heart of idol worship celebrating the fertility goddess Artemis.
So it was that many aspects of the worship of the image of Artemis that “fell from heaven,” such as processions, were integrated into Mary worship. (Acts 19:35) Another practice that crept into Christian teaching was the use of images of Mary and others in worship.
Compare these Bible verses: Matthew 13:53-56; Mark 3:31-35; Luke 11:27, 28
Mary was the mother of the Son of God, not of God himself. The Trinity myth gave birth to the worship of Mary as the Mother of God
Info From: Jehovah's Site