St. Athanasius, also called Saint Athanasius of Alexandria or Saint Athanasius the Apostolic, (born 293, died 373), theologian, ecclesiastical statesman, and Egyptian national leader. He was the chief defender of Christian orthodoxy in the 4th-century battle against Arianism, the heresy that the Son of God was a creature of like, but not of the same, substance as God the Father.
In Athanasius’s system, the Son of God, the eternal Word through whom God made the world, entered the world in human form to lead men back to the harmony from which they had fallen away. Athanasius reacted vigorously against Arianism, for which the Son was a lesser being, and welcomed the definition of the Son formulated at the Council of Nicaea in 325: “consubstantial with the Father.” (Britannica Encyclopedia)
The doctrine of the trinity, deep-seated in orthodox Christianity, was under attack in the 4th century church. The most virulent and damaging attacks where internal not external. Flesh is prone to the sin of shaping the gospel to fit the terms of men and not the eternal truth of God. Arius, a contemporary of Athanasius taught that Christ was of a lower nature than God the Father since he was the “begotten” Son of God. In other words, Christ was not pre-existent. The doctrine of the Trinity was at stake which meant the gospel was at stake.
The doctrine of the Trinity is difficult to understand and a great mystery but it is the self-revelation of God given to us in the Scriptures. We must take God at his word. Our very souls are at stake in the fight for the truth.
Take time to study church history. Learn of the faith of our church fathers as they contended for the faith as given to the Apostle’s by our Lord Jesus Christ. The truth will make you free!