St. Athanasius writings were also responsible for much of the development and understanding of the doctrine of the Holy Trinity. In the Liturgy of Hours, the reading for Trinity Sunday is taken from St. Athanasius’ First Letter to Serapion in which he writes:
It will not be out of place to consider the ancient tradition, teaching, and faith of the Catholic Church, which was revealed by the Lord, proclaimed by the Apostles and guarded by the Fathers. For upon this faith the Church is built, and if anyone were to lapse from it, he would no longer be a Christian, either in fact or in name…We acknowledge the Trinity, holy and perfect, to consist of the Father, the Son, and the Holy Spirit. In this Trinity there is no intrusion of any alien element or of anything from outside, nor is the Trinity a blend of creative and created being (note: Christ’s Divinity here). It is a wholly creative and energizing reality, self-consistent and undivided in its active power, for the Father makes all things through the Word and in the Holy Spirit, and in this way the unity of the Holy Trinity is preserved…”
How would any of you describe the Holy Trinity?
One time I was having a discussion with an atheist who had popped in the comment section of my blog who presented a challenge to all Christians. The challenge stated, “Name one unique idea created by Christianity.” After some other bloggers had offered ideas that were dismissed, and after I had presented Transubstantiation— only to be dismissed (even though it is unique)— I also presented the most glaring central doctrine of the Church, The Holy Trinity. However, the atheist rejected this as not being an original idea as he gave what he referred to as the Hindu trinity known as Trimurti. After I had looked into the Trimurti, I concluded that the Christian Trinity is truly unique, and this comparison to the Trimurti was a false equivalent.
Now to claim this is a false equivalent, one must have a better understanding of the most Holy Trinity. In the case of the Trimurti, the three gods are exactly that, three distinct gods that are reincarnated into an avatar known Datta, but regardless, Brahma still takes center stage in that religion. I explained their difference ultimately using the Athanasian Creed, Fr. Rengers reminds us of the Athanasius Creed, “consisting of 40 rhythmic statements, had been used in the Sunday Office for over a thousand years.” —which I wish we would use more often— “So the Father is God, the Son is God, and the Holy Ghost is God. And yet they are not Three Gods, but One God…So there is One Father, not Three Fathers; one Son, not Three Sons; One Holy Ghost, not Three Holy Ghosts. And in this Trinity none is afore or after Other, None is greater or less than Another.”
During the conversation, I wish that I had the modern example given by Michael Pennock in This is Our Faith of a woman who is three different persons, although she is one woman. She is a Mother, a wife, and friend. I also wish I was more familiar with St. John’s of Damascus example, “The Father is the sun with the Son as ray and the Holy Spirit as heat.” All very distinct concepts, but from one source, and with one will. It is entirely different, a central doctrine and great mystery that is truly original to Christianity.
Finally, a great foundation for understanding the Holy Trinity rests in focusing on the Incarnation, The Word of God, Christ Jesus, Our Lord and Savior. Of course, as I’ve mentioned previously, unless we are fluent in ancient languages, we must read St. Athanasius in translation. However, one of the greatest teachers of our faith, and perhaps one day will be honored as a Doctor of the Faith, Bl. John Henry Newman writes on the Incarnation:
“This was the new and perfect tabernacle into which He entered (the body); entered, but not confined, not to be circumscribed by it. The Most High dwelleth not in temples made with hands; though His own hands ‘made it and fashioned it,’ still he did not cease to be what He was, because He became man, but was still the Infinite God, manifested in, not altered by the flesh. He took upon Him our nature, as an instrument of His purposes, not as an agent in the work. (The Incarnation is not a creature) What is one thing cannot become another; His manhood remained human, and His Godhead remained divine.”
 Rengers and Bunson, 8.
 Dave Armstrong, Quotable Newman (Sophia Press: Manchester, 2012), 197.