First Council of Nicaea

=== Trinity ===
The Council of Nicaea dealt primarily with the issue of the [[deity of Christ]]. The term "Trinity" was already in use, with the earliest existing reference being by [[Theophilus of Antioch]] (AD 115–181), referring to God, the Logos, and Sophia<ref>{{Cite web |title=Philip Schaff: Fathers of the Second Century: 0107=101 – Christian Classics Ethereal Library |url=https://ccel.org/ccel/schaff/anf02/anf02/Page_101.html |access-date=2023-04-27 |website=ccel.org}}</ref> (Father, Son and Holy Spirit, as the Holy Spirit was referred to by several Church fathers), though many scholars believe that the way the term was used indicates that it was known previously to his readers. Also, over a century before, the term "[[Trinity]]" ({{lang|grc|Τριάς}} in Greek; {{lang|la|trinitas}} in Latin) was used in the writings of [[Origen]] and [[Tertullian]], and a general notion of a "divine three", in some sense, was expressed in the 2nd-century writings of [[Polycarp]], [[Ignatius of Antioch|Ignatius]], and [[Justin Martyr]]. In Nicaea, questions regarding the Holy Spirit were left largely unaddressed until after the relationship between the Father and the Son was settled around the year 362.<ref>{{harvnb|Fairbairn|2009|pp=46–47}}</ref> The doctrine in a more full-fledged form was not formulated until the [[Council of Constantinople (381)|Council of Constantinople]] in 381<ref>{{harvnb|Socrates|loc=Book 2, Chapter 41}}</ref> and a final form formulated primarily by [[Gregory of Nyssa]].<ref>{{Cite book|last1=Schaff|first1=Philip|url=https://books.google.com/books?id=AIAXAAAAYAAJ&pg=PA477|title=A Select Library of Nicene and Post-Nicene Fathers of the Christian Church: Gregory of Nyssa: Dogmatic treatises, etc. 1893|last2=Wace|first2=Henry|date=1893|publisher=Christian literature Company|language=en}}</ref>