Did Mary have anything to do with Jesus “being of one substance with the Father”?
AMEN! Great and Godly question that, God willing, will lead them from the darkness into the light.
“AMEN! Great and Godly question that, God willing, will lead them from the darkness into the light.”
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...and was incarnate by the Holy Spirit of the Virgin Mary, and was made Man.
You forgot this part of the Creed. Although the Holy Spirit effected the Incarnation, it was from Mary that Jesus took his body. He also has a human soul. However, He is one Divine Person with two natures, Divine and human, not two persons.
Mary is not merely the mother of his human nature, she is the mother of Him. From the moment of the Incarnation, Mary became His mother in the true sense of the word. Since Jesus is God (remember, He is one Person, not two!), and Mary is His mother, than she is the Mother of God.
Not of the Trinity, of course, or even of the Son from eternity (that would be absurd) but of the Son of God made Man. He did not cease to be God when He became Man. That's the crucial point here. One person, remember! To believe otherwise is to fall for the heresy of Nestorianism, which was condemned early on. No mainline Christian church believes in this heresy anymore. No mainline church has believed in this heresy for the past 1500 years.