Mary is not the Mother of God. Mary is a fallen human being like every other fallen human being, saved by grace alone.
Your repetitive verse from Luke does not reflect the abomination Rome tries to create in place of a simple Jewish girl blessed by God to carry the Christ child to term.
http://www.newadvent.org/fathers/3810.htm
And since the holy Virgin brought forth corporally God made one with flesh according to nature, for this reason we also call her Mother of God, not as if the nature of the Word had the beginning of its existence from the flesh.
For “In the beginning was the Word, and the Word was God, and the Word was with God,” and he is the Maker of the ages, coeternal with the Father, and Creator of all; but, as we have already said, since he united to himself hypostatically human nature from her womb, also he subjected himself to birth as man, not as needing necessarily in his own nature birth in time and in these last times of the world, but in order that he might bless the beginning of our existence, and that that which sent the earthly bodies of our whole race to death, might lose its power for the future by his being born of a woman in the flesh. And this: “In sorrow you shall bring forth children,” being removed through him, he showed the truth of that spoken by the prophet, “Strong death swallowed them up, and again God has wiped away every tear from off all faces.” For this cause also we say that he attended, having been called, and also blessed, the marriage in Cana of Galilee, with his holy Apostles in accordance with the economy. We have been taught to hold these things by the holy Apostles and Evangelists, and all the God-inspired Scriptures, and in the true confessions of the blessed Fathers.