At the time of the Council of Ephesus, Theotokos was understood to mean that Mary was “mother of God,” but not in the sense that Jesus received his divine nature from Mary in any way. It simply meant that Mary, being the mother of Jesus, was the “mother of God” in that sense. Jesus is God and Mary is his mother, touching his human nature. There was no confusion at Ephesus or Chalcedon that this title was meant to ascribe any notion of deity to Mary. It simply articulated the fact that she was the earthly mother of the One Who was God Incarnate. Historian Jaroslav Pelikan has given a very good translation of Theotokos, one that accurately captures this historical understanding, “the one who gives birth to the One Who is God” (Mary Through the Centuries, New Haven, Conn.: Yale University Press, 1996, pg. 55). Given this understanding, historically there has been no official Protestant objection to the title “mother of God.” Obviously, this title could be understood to mean much more than it was understood to mean at Ephesus and at Chalcedon, but the words in and of themselves, properly qualified and defined, are not an occasion of controversy.
The Roman Catholic Church at some point began to co-opt this basic concept of Mary as the “Mother of God” and made devotion to Mary an integral part of worship (CCC 963, 971, 2677). The “Hail Mary” concludes with a petition for Mary to “pray for us sinners, now and at the hour of our death.” Protestants find this problematic. Attributing intercessory work to Mary draws objections from the vast majority of Protestants. They argue that viewing Mary as one who intercedes for us either now or at our deaths, makes Mary a kind of co-mediator of our redemption (cf. CCC 618, 964, 968, 970).
Generally speaking, Protestantism insists that Jesus is the sole mediator between God and man (I Timothy 2:5). Although, of course, the Holy Spirit also intercedes for us (Romans 8:26).
Circling back to each system’s approach to Scripture, the fundamental question that modern Roman Catholics and Mormons are obligated to answer is: Does the Holy Bible, as we have it today, contain enough information for a person to understand how to be eternally saved?