I don't understand what you're getting at.
John 14:1-11.
Thomas wasn’t an atheistic or an agnostic. He believed in the same God Jesus does prior to his comment to Jesus in John 20:28. If he didn’t go from believing God is one person to believing that God is two persons (and I agree that he didn’t) then he retained his belief in God being only one person. What then changed?
I categorically reject the unitarian view.
Then you categorically reject Jesus’ view. His God was, is, and always will be only one person, the Father.
Jesus Himself says, "My Father and your Father, My God and your God".
So his God and his followers God is only one person, the Father.
Yes. And he is only one person.
b. No. There is one God. The Father is God, Jesus is God, and the Holy Spirit is God.
I agree that there is no God besides Jesus’ God.
The Father is Jesus’ God.
Jesus is not Jesus’ God.
The Holy Spirit is not Jesus’ God.
I’ll throw in for good measure that the Trinity is not Jesus’ God.