The Father of God the Son is God the Father. DUH.
The phrase "Mother of God" originated in the Council of Ephesus, in the year 431 AD. It occurs in the Creed of Chalcedon, which was adopted by the council in 451 AD.
And Chalcedonian Christology is what all orthodox Protestants supposedly affirm.
The purpose of this statement originally was meant to emphasize the deity of Christ over against the teaching of the Nestorians whose teaching involved a dual-natured Jesus.
Wrong. All orthodox Christians believe in a "dual-natured Jesus". Nestorians believed in a Jesus who was two persons sort of "stuck together".
Their teaching was that the person born of Mary was only a man who was then indwelt by God.
Correct. This also seems to be the error of the writer, as he makes clear later!
The title "Mother of God" was used originally to counter this false doctrine.
The title Theotokos ("God-bearer"), preceded Nestorius, which is why his rejection of it caused scandal.
Mary certainly did not give birth to God. In fact, Mary did not give birth to the divinity of Christ. Mary only gave birth to the humanity of Jesus.
And here's the Nestorian part. If Mary did not give birth to God, then the Jesus she gave birth to was not God. And if the divinity of Jesus was not born (NB, I said "born," not "created" ... there's a very big difference) in the stable at Bethlehem, where was It and what was It, exactly?
He was divine God in a flesh body. This is what Mary gave birth to.
First he says Mary didn't give birth to God. Now he says she did. This piece is full of error and confusion!