What is the origin of the Doctrine of Trinity? My understanding is that "Trinity" is not is not used in the Christian Bible to define the three hypostases: God, Christ, and Holy Spirit.  What then is the historical origin of the Doctrine of the Trinity?

Put another way, when and from whom did the word "Trinity" come about in relation to the hypostases?  Is there a reason "Trinity" appears in the Christian lexicon rather than referring to the specific hypostasis?
The Trinity described:
The Athanasian Creed, formulated a few hundred years after the death of Jesus, defined the Trinity this way: “The Father is God: the Son is God: and the Holy Ghost is God. And yet they are not three Gods: but one God.”
Did Jesus start the Trinity?
Many would say that it's origin started with Jesus Christ, however that would conflict what the bible say even about his &quot;own&quot; origin (creation) about him being equal:

Colossians 1:13-15
13. Who hath delivered us from the power of darkness, and hath translated us into the kingdom of his dear Son:
14. In whom we have redemption through his blood, even the forgiveness of sins:
15. Who is the image of the invisible God, the firstborn of every creature:
16. For by him were all things created, that are in heaven, and that are in earth, visible and invisible, whether they be thrones, or
dominions, or principalities, or powers: all things were created by
him, and for him:

Was the Origin of the Trinity in the bible?
No where in the scriptures does it make mention of Trinity.
In its 1999 issue on the Trinity, The Living Pulpit observed: “Sometimes, it seems that everyone assumes that the doctrine of the trinity is standard Christian theological fare,” but it added that it is not “a biblical idea.”
“The doctrine of the trinity . . . is not a product of the earliest Christian period, and we do not find it carefully expressed before the end of the second century.”—Library of Early Christianity—Gods and the One God.
Where then could the Origin of the Trinity come from?
In his book The Church of the First Three Centuries, Dr. Alvan Lamson states that the doctrine of the Trinity “had its origin in a source entirely foreign from that of the Jewish and Christian Scriptures; that it grew up, and was ingrafted on Christianity, through the hands of the Platonizing Fathers.”
Who were these “Platonizing Fathers”? They were apostate clerics who were infatuated with the teachings of pagan Greek philosopher Plato.
The Platonic trinity, itself merely a rearrangement of older trinities dating back to earlier peoples, appears to be the rational philosophic trinity of attributes that gave birth to the three hypostases or divine persons taught by the Christian churches. . . . This Greek philosopher’s [Plato’s] conception of the divine trinity . . . can be found in all the ancient [pagan] religions.”—Nouveau Dictionnaire Universel (Paris, 1865-1870), edited by M. Lachâtre, Vol. 2, p. 1467.
History shows that the ancient civilizations and cultures that believed in a Triad god or gods were: Assyria, Babylon, Egypt, Greece, Rome which all were conquering nations, one after another, could have carried their beliefs into Christianity after Jesus' death - during the time of the Romans and of which historically were Pagans.