Of all the dogmas that most offend anti-Catholics and are misunderstood by non-Catholics are the dogmas concerning the Blessed Virgin Mary. Some people have accused Catholics of putting the Blessed Mother on par with Christ and the Blessed Trinity. Nothing could be further from the truth. All the Marion dogmas have their basis in Our Lord Jesus Christ. The most obvious one is the dogma that states that Mary is the Mother of God
In 431, the Council of Ephesus declared Our Lady to be the Mother of God to combat a heresy known as Nestorianism. This heresy denied that Our Lord was fully God and fully man because He had a human mother. So, to ensure that this heresy wouldn't pop up again, Mary was declared the Mother of God.
In spite of this evidence, many non-Catholics find it offensive. They misunderstand what it really means. Some have this wacky idea that Catholics believe that Mary lived before God and therefore is a goddess. Nothing could be further from the truth. By stating that Mary is the Mother of God, Catholics are reinforcing Christ's divinity. Since Mary is the Mother of Jesus and Jesus is God, then Mary is the Mother of God. That is, the Mother of the second person of the Blessed Trinity.
Another objection is: where does it say that in the Bible? The evidence that Mary is the Mother of God is very biblical. In Luke 1: 43, Elizabeth greets Mary by saying, 'Who am I that the Mother of my Lord should come to me?" It is obvious from this passage that Elizabeth is calling Mary the Mother of God (my Lord). Of course, the very fact that Our Lord Jesus Christ is the Word Incarnate, second person of the Blessed Trinity makes Mary the Mother of God because she is Jesus' Mother.
No one should be fearful or object to this dogma. All it does is reinforce that Jesus is God and man. This is something that no protestant would object to nor deny. The only reason that it is, is because of the misunderstandings of the dogma itself. However, if it is studied more carefully, protestants also will believe that Mary is the Mother of God and thus another misunderstanding would be cleared up.