Just how important is Mary to many Catholics? Mary and Elizabeth are wonderful heroines in Luke's account. He loves the faith of these women. The thing that impresses him most, it appears, is the lowliness and cheerful humility of Elizabeth and Mary. Elizabeth says (1:43): "And why is this granted to me that the mother of my Lord would come to me? And Mary says (1:48): The Lord has regarded the low estate of His handmaiden." The only people whose soul can truly magnify the Lord are people like Elizabeth and Mary--people who acknowledge their lowly estate and are overwhelmed by the condescension of the magnificent God.
From: Lutheran Church Doctrine of Beliefs, LCMS. The first Protestants "never objected to denoting the Virgin Mary as the "Mother of God" (theotokos, "God-bearer"), since she was the mother of Jesus and Jesus was and is indeed God. Since the Son of God was and is sinless, it is evident that some miraculous "exception" was made in the conception of Jesus through Mary that prevented original sin from tainting the Christ-child."
Although the first Protestants again reaffirmed the Apostolic Christian position that Mary had no other Children, and the 'Brothers' of our Lord were either cousins or children of Joseph from another marriage. It was not until the post-reformational era that these ideas surfaced. Again, as Sola Scriptura allows, modern Protestants reject not only Apostolic Christianity but also the ideas of their own reformers. (less info)