There's a reason for history books.
A faction of Christians held that Jesus was homo-ousios (of the same essence) as the Father.
The opposing group said Jesus was a "created being" made by God. Jesus as an inter-mediator was subordinate to God the Father and therfore hetero-ousios (of a different essence).
The debate wasn't new. In fact, the council of Antioch (264-272) explicitly rejected the homo-ousios formulation. But the food fight continued over the next 40 years and threatened to split the nascent Church.
That is, until the council of Nicea in 325CE.
The hetero-ousios group were now called the 'Arians' due to it's chief proponent Arius -- a presbyter in Alexandria. The homo-ousios group led by Bishop Alexander of Alexandria and his deacon Athanasius, were the Trinitarians -- beleiving the Trinity.
Five years before Nicea, Bishop Alexander had condemned Arius and forced him to take refuge with Eusebius of Caæsarea (the historian), and later with Eusebius of Nicomedia (the Bishop). Bishop Eusebius influenced Constantine (the Emperor) step in to settle the dispute.
A pagan, the Emperor Constantine thought the whole thing was rather silly and of no practical importance. At first he asks Alexander and Arius to come to a philoshopical compromise. When that proves impossible, Constantine (probably with Pope Sylvester in agreement) calls for a ecumenical council to reestablish the religious peace.
At Nicea, Constantine refused to entertain charges and counter-charges of apostasy made by the bishops against each other and ordered them to get to business. At the synod before the emperor arrived, debate was evenly divided, but by the time Constantine showed up, it was clear that the majority were supporting Bishop Alexander's group.
Constantine went with the majority (the Trinitarian creed) and exiled Arius along with Theonas of Marmarica and Secundus of Ptolemais, and later Bishop Eusebius.
By 330CE, all the Arians (except for Arius, who was poisioned on his way back), had been recalled from exile and back in good graces of the Church and Emperor.
Although requested by the Emperor to readmit former Arians to ecclesiastical communion, Athanasius refused.
In 335, based on charges from Bishop Eusebius, the Tyre Synod declared Athanasius (now Bishop of Alexandria), was anathema and he in turn was exiled.
So yes.
The question was decided in the 4th century for political reasons.
It certainly isn't true that "The doctrine of the divinity of Christ was invented in the 4th Century as a political power play." History is clear that this was already the Christian doctrine.