There is an excellent exposition of the Marian Theology given byPope John in his Catechesis , which was the 37th in the series on the Blessed Mother and was given in Italian. This is actually an exposition of the historical developement of deification of Mary and do not require additional coments to see through the falacy of the arguments.

"1. Contemplation of the mystery of the Saviour's birth has led Christian people not only to invoke the Blessed Virgin as the Mother of Jesus, but also to recognize her as Mother of God. This truth was already confirmed and perceived as belonging to the Church's heritage of faith from the early centuries of the Christian era,  until it was solemnly proclaimed at the Council of Ephesus in 431 and it is affirmed that Jesus is God (Jn 20:28; cf. 5:18; 10:30, 33) Mary is in any case presented as the Mother of Emmanuel, which means "God with us" (cf. Mt 1.22 23)"

We notice that Pope John starts with a statement that it had been always believed that Mary was the mother of God. However as he says later this stand and declaration was made only in the Council of Ephesus. When we look at the historical situation in which it was annouced we will see the real meaning of why this was made and what the council fathers meant by it. . At any rate such a concept never even existed when Jesus was alive or at the Apostolic Age after the resurrection of Jesus. Mary is mentioned in the Acts only once and that was as part of the Church. {Act 1:14 They all joined together constantly in prayer, along with the women and Mary the mother of Jesus, and with his brothers.}

The declaration was made on the background of Arian and Nestorian theologies. The two dimensional view of the Western world had a problem. How can Jesus be both God and Man. If he is man, he is not God; and if he is God he is not man. However we know that the two are in totally different dimensions. Man is never part of the God dimension except in the New Ager philosophy, which Christians reject. Hence for a transcendant God to be immanent in creation is not a contradiction. Yet he transcends the creation. The western mind is incapable of understanding this. In Rome and Greece there were gods and these gods had children from humans. The offsprings were always mighty men and with super powers but never gods. For a hindu who distinguishes the Paramatma from Jeevatma (they are called Dvaitha Philosophers) had no problem in it. Krishna was an avtar of God. But Krishna's mother Yasodha had no divinity in her. She simply provided the body. This is actually the concept of avtar or incarnation. In the west the concept of avtar never existed. This produced several heresies. The most powerful of them was the Arian heresy - a clever solution to this paradox. They considered Jesus as anointed one. So Mary would be Christotokos - Mother of Christ. Jesus then was the anointed one - the Mesia - the Christos. But he was a man - fully human. The Apostolic tradition claims that Jesus was fully man and fully God. The correct rendering would have been simply Mother of Immanuel - Mother of God with us. Nestorian approach was slightly different. Nestorius was the Bishop of Constantinople.  His basic concern was to safeguard the humanity of Jesus, without which redemption cannot be talked of.  He sparked off a controversy on the use of the phrase Theokotos which literally means “God bearer” or “Mother of God.”  as applied to Mary.  Nestorius preferred the use of the word Christotokos which means “Christ bearer or Mother of Christ”  This would preserve humanity of Jesus and would make Mary the mother of Jesus and not of God and will avoid controversey.  The really difficult concept of Jesus as Perfect Man and Perfect God was explained by Nestorius as Jesus having two natures within himself.  This would mean two personalities within Jesus. Evidently these were rational attempts to explain a concept that was beyond them.   There were internal politics as anyone can presume.  The Eastern Emperor Theodosius II (408-450) called for a council in Ephesus.  The Alexandrian bishops attended in full strength.  Nestorius refused to come fearing his life.  Bishops from Antioch came, but the council met and took decision before their arrival.  Cyril of Alexandria read a statement of union of two natures and the coucil approved it.  Bishops from Antioch came but it was too late to reverse the decision.  Nestorius was  deposed and exiled.  But the controvesey continued with the rise of Monophysis theory (Christ had only One nature ). It must be emphasized here that Nestorius was not a Monophysis though many would try to put him as such. His concern was genuine and it is borne out by the current developments.  Emperor Theodosius  called another council in Ephesus in 449.  Bishop Cyril died and Dioscorus was the new Bishop of Alexandria.  He brought with him an army of monks.  Bishop of constantinople was beaten up and was murdered by the Egyptian delegation in the streets.  In the third council in Ephesus Bishop Leo I of  Rome put up the stand that Jesus was perfect God and perfect Man and stated doctrinally that there was no conflict in this approach.

Let me put these arguments in perspective: 

 But we should also note that this argument could also follow the other route. 

 If there is no conflict in these it would mean Theokotos = Christokotos

and there should be no confusion on what that means.

Mary gave the body of Jesus, not the soul or the spirit. In order to understand the creation process we should go back to creationof Adam. Adam was created out of the earth and God breathed on him. The spirit that was breathed into him made him a living soul. This spirit was not the Spirit God = Holy Spirit but spirit from God. The equation is therefore
Body + spirit ------> Living Soul (Man)

In that sense Adam was the son of God and Mathew says so in the genealogy of Jesus.

But in the case of Jesus the spirit was the Holy Spirt and the equation becomes
Body + Holy Spirit --->Son of God (God).

There is no doubt that Jesus grew up as a man. In that process he develops the Soul which was unique. But he was still God. It should be borne in mind that though Jesus was God, while he was on the earth he never used his equality with God and was totally  human.  This concept of emptying  himself up is forgotton by the mariolators .

Phill 2:6-8 Who, being in very nature God, did not consider equality with God something to be grasped,but made himself nothing, taking the very nature of a servant, being made in human likeness.And being found in appearance as a man, he humbled himself and became obedient to death-- even death on a cross!. The question I have always pondered over was whether Jesus knew he was God when he was an year old, over even when he was at the temple arguing with the teachers?.

The Ephesus Council's concern was the affirmation that Jesus was God and not that Mary was Mother of God. In fact Ephesus Council understood it that way. Even Pope John acknowledges this basic fact.

But the danger was that this clear interpretation was lost in the ensuing years. As an example in the introduction of Pope John's Catechis the introducer makes this remark:."The Council of Ephesus taught that Mary is truly the Mother of God, since she gave birth to the Second Person of the Trinity who became man for our sake".

The confusion starts here. " she gave birth to the Second Person of the Trinity" is a confusion in the concept of incarnation. She gave birth to the incarnation of the second person in trinity in the human realm or dimension should be the correct phrasing. As it reads it simply means :

Mary gave birth to God, who is the second person in the Trinity.

It implies that there was a time when the Second Person of the Trinity was not and Mary was before him.

What does that lead to. It simply means that Mary was before all creation( In actual fact Christians cannot avoid the fact that the second Person in Trinity did the creation and Mary was created by the Second Person in the Trinity and Mary came into existence in history long after the creation). In other words it would imply that Mary was pre-existant even before the creation - She was indeed a Goddess. Remember that the Catechism does not state it so clearly here. But for anyone careful enough to see the argument sees in this statement a built in concept of Goddess though it is not explicitly stated. The problem is already built in the title Mother of God. The seed was sown and it grew into a big tree. It is coming in a long series of steps. But it is bound to come. Its inevitable culmination is a known fact.

Forgetting what may come into effect let us turn to the argumetn itself. The argument here runs like this:

Mary was the Mother of Jesus.

Jesus is God.

Therefore Mary is the Mother of God.

This logic is a very dangerous logic. Extend this logic and we arrive at several contradictions.

The other day I came across a car sticker which said the same thing. It said, "My Goddess gave birth to your God." (The Hindus could really claim that because, in Hinduism the first appearance of Brahman was in the form of a woman. She became the Mother of all things material and immaterial and living and non-living.

Mary was the mother of God.  Who was his father? There is no question that Father God  -- Yvh - was Jesus’ Father.  What does that make Mary?  Mary is then the wife of God.  This makes her the consort of Yvh - simply a Goddess coequal with the Father.

It does not stop there.  If Jesus was God.  This God was the son of Mary and Mary is the wife of God, Mary becomes the wife of Jesus God.

This teaching is already immanent in the logic and is unequivocally expressed in the contemperory artistic expressions.  The cornonation of Mary in Heaven where Jesus sitting besides Mary crowning her is the typical picture of crowning of a Queen on earth.  This is done none other than the King himself.  She is crowned as the Queen of Heaven.  Who is the King of  Heaven.  King of Kings and Lord of Lord is none other than Jesus.  That will make Jesus the husband of Mary.  But Jesus is indeed the son of  Mary.  We clearly see that the Son married the Mother.  This is not new.  It is an old story.  A repetition of the ancient Nimrod-Semiramis-Tammuz story..

We cannot avoid this contradiction if the title Mother of God is interpreted as one who gave birth to God. If you interpret it that way the only solution to the problem is to make Mary Goddess who existed even before the Son. Evidently the intentions and interpretations of Ephesus Council was far from that. It only wanted to assert that Jesus was indeed fully God and also fully Man. In asserting only one aspect of Jesus - his divine nature in disregard to his human aspect the council has created a huge problem. But anyone who knows the context (The Arian and Nestorian heresies) and the intentions of the resolution resolves the problem easily. But time causes forgetfulness and it snow balled into a crisis. As we will see in the Catechis, Pope Paul picks up the next step in Marian theology along that line.

Today the tables are turned. Look at the following quotation from one of the "What Catholics Believe" sites:

"But because more people believed that Mary was really the Mother of God , the Church was able to condemn the error." They have put the cart indeed before the horse. In contrast Pope John himself corrects the misunderstanding thus: "Mary's divine motherhood refers only to the human begetting of the Son of God but not, however, to his divine birth. The Son of God was eternally begotten of God the Father, and is consubstantial with him. Mary, of course, has no part in this eternal birth. However, the Son of God assumed our human nature 2,000 years ago and was conceived by and born of Mary." So far it is wonderful.But then he goes on to say "Thus having given birth, according to his human nature, to the person of Jesus, who is a divine person, Mary is the Mother of God." which evidently is a contradiction The term was coined to emphasize the divinity of Jesus and not to emphasize the Motherhood of Mary in relation to Jesus. . Does that term support the explanation? Does that make Mary cosubstantial with God? How far can the true meaning be misinterpreted by that title is evident.

I am just stating that the choice of the title "Mother of God" was unfortunate as the title "Mother of Christ" also would have been. The appropriate title could only have been "Mother of Jesus" or "Mother of Immanuel" which would have given the full deity of Jesus and the full manhood of Jesus simultaneously.