Despite the name, The Athanasian Creed probably was not written by Athanasius of Alexandria—though it is in line with what he taught. It seems to have developed sometime around the 400s-500s as a response to the same heresies addressed by The Chalcedonian Creed, as well as heretical movements like Sabellianism, Monarchianism, and Patripassianism, which explicitly denied the Trinity. This statement explains the orthodox understanding of God’s triune nature and restates the Christological aspects of The Nicene Creed, arguing that one cannot reject these tenets and be a Christian.
Whosoever will be saved, it is necessary that he holds the universal faith; for, unless one keeps it whole and undefiled, without doubt, he will perish eternally. And this is the universal faith:
We worship one God in the Trinity and the Trinity in unity, without confounding the Persons or dividing their substance.
The Father is one Person, the Son is another, and the Holy Spirit is another.
But the Godhead of the Father, of the Son, and of the Holy Spirit, it is all one; their glory is equal, and their majesty is co-eternal.
Such as the Father is, so is the Son, and so is the Holy Spirit; the Father is uncreated, the Son is uncreated, and the Holy Spirit is uncreated; the Father is infinite, the Son is infinite, and the Holy Spirit is infinite; the Father is eternal, the Son is eternal, and the Holy Spirit is eternal.
And yet, they are not three eternals, but one Eternal. Likewise, there are not three uncreated or three infinites, but one Uncreated and one Infinite.
So likewise, the Father is almighty, the Son is almighty, and the Holy Spirit is almighty. And yet, they are not three almighties, but one Almighty.
The Father is God, the Son is God, and the Holy Spirit is God. And yet they are not three gods, but one God.
The Father is Lord, the Son is Lord, and the Holy Spirit is Lord. And yet they are not three lords, but one Lord.
For just as we are compelled by Christian truth to confess each Person by Himself to be God and Lord, we are likewise forbidden by the universal faith to say that there are three gods or three lords.
The Father is made by no one: He was neither created nor begotten.
The Son is begotten of the Father alone: He was neither made nor created.
The Holy Spirit proceeds from the Father and the Son: He was neither made, nor created, nor begotten.
So, there is one Father, not three Fathers; one Son, not three Sons; one Holy Spirit, not three Holy Spirits.
And in this Trinity, no one is before or after another; no one is greater or less than another. All three Persons are co-eternal and co-equal.
So that in all things, as before said: the Unity in Trinity, and the Trinity in Unity, is to be worshiped.
He therefore that will be saved, let him thus think of the Trinity.
Furthermore, it is necessary to his everlasting salvation that he also believe truly the Incarnation of our Lord Jesus Christ.
For the true faith—which we believe and confess—is that our Lord Jesus Christ, the Son of God, is God and man.
He is God, of the substance of the Father, begotten before the worlds, and man, of the substance of His mother, born in the world.
He is perfect God and perfect man, subsisting of a rational soul and human flesh.
He is equal to the Father, with respect to His godhood, and inferior to the Father, with respect to His manhood.
Although He is God and man, yet He is not two persons, but one Christ.
He is One, not by conversion of the Godhead into flesh, but by the assumption of the manhood into God.
He is One altogether, not by confusion of substance, but by unity of Person.
For as the rational soul and flesh is one man, so God and man is one Christ.
He suffered for our salvation, descended into the grave, and rose again the third day from the dead.
He ascended into heaven, and He sits at the right hand of God the Father Almighty.
From there, He will return to judge the living and the dead.
At His return, all men shall rise again with their bodies and shall give account for their own works.
Those who have done good shall go into life everlasting, and those who have done evil, into everlasting fire.
This is the universal faith; unless a man truly believes it, he cannot be saved.