Massacre of the Innocents

[Minimalist]

Part of Ehrman's discussion of the doctrine of the Trinity from "Jesus Interrupted."

And so the emperorcalled a meeting in Nicaea of the most important Christian bishops
in the empire, in order to debate the issues and to make a judgment
to be binding on all Christians. This was the famous Council of
Nicaea of the year 325 CE.

In the end the council voted for Athanasius’s position. Contrary
to what is sometimes said, it was nearly a unanimous decision, not
a close vote. Still, even after that day the debates continued, and for
a while in the fourth century it looked as though the Arians were
going to emerge victorious after all. But eventually the orthodox
position was that of Athanasius. There are three persons in the Godhead.
They are distinct from each other. But each one is equally God.
All three are eternal beings. And they all are of the same substance.
This, then, is the doctrine of the Trinity.

It is quite a development from anything found in the New Testament,
where there is no explicit statement of anything of the sort.
Not even in a document like the Gospel of John, where Jesus is
thought of as divine, is there any discussion of three being one in
substance. As you might expect, later scribes of the New Testament
found this lack disturbing, and so in one place at least they inserted
an explicit reference to the Trinity (1 John 5:7–8).9 The Trinity is
a later Christian invention, which was based, in the arguments of
Athanasius and others, on passages of Scripture but which does not
actually appear in any of the books of the New Testament.

Your core beliefs were decided by a committee vote to please a Roman Emperor, Huggy.  And they phonied up some of your precious scripture to say so.  I hope you are proud.  Meanwhile, in spite of Nicaea Arianism continued to thrive for centuries particularly among the barbarian tribes who swept in and overran the Western Roman Empire from Gaul to Spain to North Africa.