Athanasius’ early life is not well-understood. He was born in the 290s in Alexandria – the intellectual center and the breadbasket of Rome in northern Africa, near what is Egypt. He studied under the great bishop Alexander and was his protégé.
In the year 325 AD, the Roman Emperor Constantine called a great council of Bishops within the
Roman Empire in the city of Nicea. This great Council began with some
administrative manners, including how to readmit lapsed Christians from the
recent persecution and solidified details on the selection of church
officials. The main event, however, was
to resolve a point of doctrine which threated to divide the church – concerning
the nature of who Jesus was. The point
of contention was the teachings of a man named Arius, voiced by Bishop Eusebius
of Nicodemia. Arius argued that the Son
was the firstborn of creation and, hence, a created being. As a created being Jesus, though greater than
all Creation, was a lesser being than the Father.
During the debate, young Athanasius – at this time a Deacon of Alexander – rose to be the chief opponent of Arianism. Athanasius’ brilliant mind argued from Scripture and from church history that the Father and the Son had always existed together eternally and coequal. He argued from Jesus’ statements such as “I and the Father are One” and from John 1, stating “…the Word was God…”. He also directly challenged his opponent to name one early Church Father who taught as he did – an argument that received no answer.
In the end, the Council of Nicea sided with Athanasius nearly unanimously. They drafted a statement which we now know as the Nicene Creed, including the verbiage about Jesus, “…begotten, not made, of the same substance as the Father, by whom all things were made…”.
Athanasius was later elevated to the position of Bishop of Alexandria, where he continued a fierce defense of sound Christian doctrine. He was persecuted in later years by Arian-leaning emperors. Arian doctrine, and its successors, have unfortunately plagued the church for years – even to the present day in the doctrines of the Jehovah’s Witness cult.
Gonzalez, Justo L., The Story of Christianity, Volume 1, HarperCollins Publishers, 1984.
https://www.thegospelcoalition.org/article/who-was-athanasius-and-why-was-he-important/