You couldn't really have a god boffing a mortal and producing a demi-god called Jesus. That had all been done before, it was a little past tense, it was an entertainment and had never lasted as a real, genuine belief system that sucked people in dominated their attention and secured devoted followers.
When you're talking the One God, you couldn't suddenly decided to have two eternal gods, and if you wanted a central authority rather than some sort of democratic process obviously there had to be some sort of begetting so that authority would remain in the same general area in the way that things obviously passed to the eldest son.
After the fiasco, the basic embarrassment, of those early Canaanite roots any thing like two gods seemed a little risky even if you did call it the Holy Spirit who'd obviously be a boy. And yes it was all very convoluted but so much better than bringing back a Mithra and an Anahita or a familiar and comforting army of evil fighting Spentas and calling them "beings worthy of worship" or "emanations of the One God." But wait a minute, thinking of them as "emanations" could provide the three legs of a milking stool.....
I'm not sure I have the patience for a discussion of the tangle of string that's the foundation of the Christian Faith. It's always referred to as incredibly complex, requiring years of study and reflection that ideally was paid for by others. Which is probably correct, you don't get a mind around something like perichoresis or Hypostatic Union in a ten minute gossip after church on Christmas Eve.
It is fascinating the effort generations of increasingly decrepit old farts have put into justifying the theme of their mission on earth which is basically to discuss the merits and demerits of Jesus' use of blessed in his Sermon on the Mount. As a top-down command it quickly gets stale but as an area of discussion I see years and years of good company,
First of all: Perichoresis, from the Greek for "rotation" or "making room for" is understood this way: "Describing the mutual indwelling and interpenetration of the three Persons of the Trinity (Father, Son, Holy Spirit), emphasizing their distinctness yet perfect unity and shared essence, as well as the union of Christ's divine and human natures."
It does sound a little like a poor excuse for being found in a nun's bedroom. What it means is that The Trinity just is and always has been the starting point for everything in the universe and because God had decided to reveal it to us by penetrating a mortal, it just showed how important we were to him, and how much he actually loved us even if occasionally we did get on his nerves and he on ours.
Second of all : "Hypostatic" from the Greek for "pertaining to substance" in the context of The Trinity means relating to the underlying substance personified by the trinity. The Father, Son and Holy Ghost are personifications. In those days substance and being didn't have the distinction it has today. Substance and essence were pretty much the same thing, in Greek it was referred to as Ousia. Hypostasis in this context are individual realities. Hence: One Ousia, three Hypostases.
When it came to the question "Is Ousia a physical substance?" There was doubt whether substance, the raw sediment, was essence. "Did what it was made of become its essence, or did it's essence become what it was made of?" Hypostasis in those days was not physical but it was Objective Reality. Ghosts, spirits, Gods, the panapoly was a fluid world of dreams and wonder. It was entirely possible for a genuine son of Zeus to stray with a mortal and produce an offspring with the mortality of a human and the powers of a God, but this wasn't actually the point, the fact that it could and might happen was the point. Do you see the beginnings of a ghost in the Ousia? The straightening of the line, the hunt for an end.
If you don't recognize the arrogance of the gigantic statement Trinatarians decided to make when in the interest of their one god, they chose to demand an adherence to a belief that declared God was a permanent unmoved mover, everlasting eternal structure, then lets add a dimension that asks "Why can't god and man go round and round in circles for ever and ever?"
My answer is power hungry megalomaniacal ass-wipes who demanded we engaged in a linear thought pattern by declaring a hypostatic union between a God and a man which put a Triadic Structure into our understanding of the universe which included us people as a central feature. In Hegelian Dialectic terms the thesis was God, the antitheses was man and the syntheses was Person or Christ.
We people were a leg on the milking stool, we were a fixture with a time-line, it was all our fault, God was a long suffering "who" and all this time we had been responsible. In reality nothing had actually changed, but under the new top-down guidelines our sins had been forgiven our new straight line of existence required us to readjust our legal systems, we were required to stop observing the logic of the feud, we were required to forgive our neighbors not demand the restoration of damages. The King, the ultimate leader wasn't God, the King was a part of each one of us up there in heaven with the Father and the Holy Ghost.
And of course we have to have a look at the Holy Ghost, ask questions, make sure we're on the same page and be polite about his purpose. His job was to give life to the Triadic Structure of the Trinity. He allowed The Trinity to be free of the tripe ridden land, it was a real thing up there, a real place, a real country up there that each one of us, whether we were lord or lady, journeyman or serf properly belonged to.