“So, Catholicism teaches that God has a a mother.”
Because Jesus is God.
“Therefore, Mary is deity and God is a finite being.”
Nope. No more than being the mother of a man makes a woman a man like her son.
John 2:1 On the third day there was a wedding at Cana in Galilee, and the mother of Jesus was there.
John 2:3 When the wine ran out, the mother of Jesus said to him, They have no wine.
Acts 1:14 All these with one accord were devoting themselves to prayer, together with the women and Mary the mother of Jesus, and his brothers.
Scripture is clear in calling Mary *the mother of Jesus*.
Or did the Holy Spirit blow it?
So tell me. If the term *mother of God* would ensure that people would understand who Jesus was, then why didn't the Holy Spirit use it?
Sounds like Oneness theology to me.