Is Mary the Mother of God? An answer to a Protestant Objection

Happy New Year's and Happy Solemnity of Mary, the Mother of God.

Today, on Facebook, I came across the following objection to Mary being called the Mother of God. In case you run across this today, or any day, here is my refutation.

The Objection (attributed to Dr. Walter Martin): "If Catholics say, 'Mary is the Mother of Jesus, therefore, Mary is the mother of God, then it also follows that we must say, 'God is Trinity; Mary is the mother of God, therefore, Mary is the mother of the Trinity.'"

Let's simplify this to a syllogism. The Catholic argument is:

Mary is the mother of Jesus
Therefore, Mary is the mother of God

Syllogisms always have three propositions (two premises and one conclusion). This type of syllogism is called an "enthymeme," i.e. one that has an unstated "hidden" premise. Why do all syllogisms have to have three propositions? To link the three terms that are present. For example, in our Catholic argument, the three terms are: "Mary," "Jesus," and "God." The "hidden" proposition must link "Jesus" to "God." Thus, the hidden proposition is, "Jesus is God." So, our syllogism is:

Syllogism 1:

Mary is the mother of Jesus
Jesus is God
Therefore, Mary is the mother of God

Fine and good. That is iron-clad logic.

Martin's argument seems, on the surface equally strong,

Syllogism 2:

God is Trinity
Mary is the mother of God
Therefore, Mary is the mother of the Trinity.

Do we Catholics have to start claiming Mary is the mother of the Father and the Holy Spirit? No. Why? Because Dr. Martin's argument depends on this argument,

Necessary, false, Syllogism 3:

Jesus is God
God is the Trinity
Therefore, Jesus is the Trinity

It is only by establishing the equivalence between Jesus and the Trinity that would require us to call Mary, if she is the mother of God, to also be the mother of the entire Trinity. Neither we Catholics, nor (I presume) Dr. Martin believe Jesus is the Trinity, therefore Martin's argument evaporates.

TL;DR - Mary being the mother of one person of the Trinity doesn't mean she is the mother of all three persons of the Trinity.

Have a holy feast day!