Sweeter: Is the Trinity Biblical?

"It's not," said some respected friends of mine (friends that I still very much respect) when I mentioned it recently. "What about the verses that talk about the Godhead?" I asked. "Well, 'the Godhead' is just another term for 'the Trinity,'" came the answer. I said, "But there are verses in the Bible that refer to the Godhead." "Are there?" they asked doubtfully. I said, "Yeah, like in Romans 1. . . ." But I didn't know any specific verses, so we moved on and started talking about something else.

But then today I looked it up, and here they are:
"For since the creation of the world His invisible attributes are clearly seen, being understood by the things that are made, even His eternal power and Godhead, so that they are without excuse" (Romans 1:20).
"For in Him dwells all the fullness of the Godhead bodily" (Colossians 2:9).

What would the Holy Spirit be if He wasn't part of the Trinity?
"Hear O Israel the Lord our God, the Lord is One" (Deuteronomy 6:4).
The Father is God (Matthew 6:8, 7:21, Galatians 1:1).
Jesus is God (John 1:1-18).
The Holy Spirit is God (John 15:26, Mark 3:29, 1 Corinthians 6:19).

What would the Holy Spirit be if He wasn't God?
The Scriptures refer to the Holy Spirit as a 'He,' not an 'it' - this makes it clear that He is a person.
There is never any suggestion that He is an angel. (If you're thinking 'spirit' always means 'angel,' then you have to assume that God Himself is a mere angel - "God is a Spirit: and they that worship him must worship him in spirit and in truth" (John 4:24).
Or maybe you're saying the Holy Spirit is just another way of talking about the Father/Spn duo? I'm sorry, but I would just have trouble understanding that one; but I do know I can be a bit slow at some stuff these days, so who knows?