Karen Armstrong writes lots about it in History of God. She's done her homework. The trinity is a political construct.

It has to do with pre-Christian traditions of Greece clashing with pre-Christian Cappodocian, (Turkish) traditions, which Christianity was adapted to.

It's got very much to do with language and how they used the terminology of god, faith, spirituality and belief. Anyhoo, it threatened to tear the east Roman empire apart and emperor Constantine threatened the quarrellers with death unless they came up with a compromise.

On one side was Arius who claimed that Jesus was not divine and that worshipping Jesus as such would be idolatry. There can only be one God.

On the other side was a variety of theories on variants on how Jesus had some divinity in him. ie was of God. Gregory of Nyssa, Athanasius, Marcellus among others belonged to this camp.

They managed to agree on that God could be felt by the worshipper when praying, ie the holy ghost. The part of God that fills the prayer when praying.

But they managed to agree on nothing much else.

This is where the concept of "the father, the son and the holy ghost" was born. It was formulated this way because it doesn't say anything and mediates between the two camps. How this purely political and not theological solution has managed to linger up until today, is just one of those mysteries in life.

Arius eventually ended up being branded a heretic, but Arianism still went strong for centuries after his deaths. Especially with the Gorths, who managed to conquer Rome.

The debate whether Jesus is of the same stuff as God still rages today.

edit: I looked through that page some more. I don't think it's supported by any biblical research. I think it's fantasy. I'm guessing somebody just read the Bible and drew their own conclusions ignoring centuries of research and material to be found on the subject. Just my guess.