The Holy Trinity

If you go looking to find god in the
Bible, you'll find him there. If you
read it with an open mind, you'll
have a different experience entirely.

I think the scholars first had to describe how Jesus is fully human and fully divine (Hypostatic Union) before they were able to describe the Trinity.

Jesus had to have two wills, one human will and one divine will, to be able to explain having holes in His hands, etc.

So one name (Jesus) controlled two wills.

They knew Jesus had to have a genetic mother to qualify as being human (His age is a little over 2028 years or so and getting older).

Humans have to be born in a womb (so far) even though His divinity of the Word has always existed.

They knew that Jesus had to be divine to explain the miracles at will, such as appearing to Thomas with holes in His hands.

There's not too many ways to explain the massive conversions to Christianity in such a short time.

Possibly two billion converts alive already (not counting deaths) and Jesus is relatively young.

So the Word (part of the Trinity) had to be incarnated in Him (John 1).

When He was preparing for death the night before He was captured, His two wills were in opposition to each other but He always submitted His human will.

The mechanism chosen was to allow access to the Holy Spirit (part of the Trinity) for all humans.

That's the good news.

I'd imagine that's how they came up with the Trinity, using similar logic.