Three beings is three gods, not one God, which is why I asked Absolutely about his comment.
The Council was held in 325 A.D.
The Council convened to discuss several matters, including, but not limited to, the teaching of Arius (Arianism), and decided that Arianism was heresy. There were many in the Church who thought Arianism was orthodoxy. Those who refused to go along with the decision were exiled. Arius and two Bishops (Theonas of Marmarica and Secundus of Ptolemaic) refused to sign.
Three Bishops (Eusebius of Nicomedia, Theognis of Nicaea, and Maris of Chalcedon) who signed later recanted. They wrote in a letter to Constantine “We committed an impious act, O Prince, by subscribing to a blasphemy from fear of you.”
Arianism later triumphed over Athanasius and his supporters, but only for a while.
This factional fighting for theological supremacy occurred after the Church parted ways with Jewish monotheism.