The so-called Athanasian Creed, also called “Quicumque” after the first word of the Latin text does not orig­i­nate with Athana­sius, but was ini­tial­ly writ­ten in Latin between the end of the 4th and the end of the 6th cen­tu­ry. It con­tains the one of the clear­est for­mu­la­tions of the mys­tery of the Trin­i­ty and the Incar­na­tion.

Who­ev­er wills to be in a state of sal­va­tion, before all things it is nec­es­sary that he hold the catholic¹ faith,
which except every­one shall have kept whole and unde­filed with­out doubt he will per­ish eter­nal­ly.
Now the catholic² faith is that we wor­ship One God in Trin­i­ty and Trin­i­ty in Uni­ty, nei­ther con­found­ing the Per­sons nor divid­ing the sub­stance.
For there is one Per­son of the Father, anoth­er of the Son, anoth­er of the Holy Spir­it.
But the God­head of the Father, of the Son, and of the Holy Spir­it, is One, the Glo­ry equal, the Majesty coeter­nal.
Such as the Father is, such is the Son, and such is the Holy Spir­it;
the Father uncre­at­ed, the Son uncre­at­ed, and the Holy Spir­it uncre­at­ed;
the Father infi­nite, the Son infi­nite, and the Holy Spir­it infi­nite;
the Father eter­nal, the Son eter­nal, and the Holy Spir­it eter­nal.
And yet not three eter­nals but one eter­nal, as also not three infin­ites, nor three uncre­at­ed, but one uncre­at­ed, and one infi­nite.
So, like­wise, the Father is almighty, the Son almighty, and the Holy Spir­it almighty;
and yet not three almight­ies but one almighty.
So the Father is God, the Son God, and the Holy Spir­it God;
and yet not three Gods but one God.
So the Father is Lord, the Son Lord, and the Holy Spir­it Lord;
and yet not three Lords but one Lord.
For like as we are com­pelled by Chris­t­ian truth to acknowl­edge every Per­son by Him­self to be both God and Lord;
so are we for­bid­den by the catholic³ reli­gion to say, there be three Gods or three Lords.
The Father is made of none, nei­ther cre­at­ed nor begot­ten.
The Son is of the Father alone, not made nor cre­at­ed but begot­ten.
The Holy Spir­it is of the Father and the Son, not made nor cre­at­ed nor begot­ten but pro­ceed­ing.
So there is one Father not three Fathers, one Son not three Sons, and one Holy Spir­it not three Holy Spir­its.
And in this Trin­i­ty there is noth­ing before or after, noth­ing greater or less, but the whole three Per­sons are coeter­nal togeth­er and coequal.
So that in all things, as is afore­said, the Trin­i­ty in Uni­ty and the Uni­ty in Trin­i­ty is to be wor­shipped.
He there­fore who wills to be in a state of sal­va­tion, let him think thus of the Trin­i­ty.
But it is nec­es­sary to eter­nal sal­va­tion that he also believes faith­ful­ly the Incar­na­tion of our Lord Jesus Christ.
The right faith there­fore is that we believe and con­fess 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 He is man of the sub­stance of His moth­er born in the world;
per­fect God, per­fect man sub­sist­ing of a rea­son­ing soul and human flesh;
equal to the Father as touch­ing His God­head, infe­ri­or to the Father as touch­ing His Man­hood.
Who although He be God and Man yet He is not two but one Christ;
one how­ev­er not by con­ver­sion of the God­Head in the flesh, but by tak­ing of the Man­hood in God; one alto­geth­er not by con­fu­sion of sub­stance but by uni­ty of Per­son.
For as the rea­son­ing soul and flesh is one man, so God and Man is one Christ.
Who suf­fered for our sal­va­tion, descend­ed to the dead, rose again from the dead,
ascend­ed into heav­en, sits at the right hand of the Father, from whence He shall come to judge the liv­ing and the dead.
At whose com­ing all men shall rise again with their bod­ies and shall give account for their own works.
And they that have done good shall go into life eter­nal, and they who indeed have done evil into eter­nal fire.
This is the catholic⁴ faith, which except a man shall have believed faith­ful­ly and firm­ly he can­not be in a state of sal­va­tion.

1. We use the term “Catholic” not in ref­er­ence to a denom­i­na­tion, but in its orig­i­nal mean­ing: gen­er­al, uni­ver­sal. There is only one church of Jesus Christ, the fel­low­ship of those who hold to “the faith which was once for all hand­ed down to the saints” (Jude 3). ↩
2. We use the term “Catholic” not in ref­er­ence to a denom­i­na­tion, but in its orig­i­nal mean­ing: gen­er­al, uni­ver­sal. There is only one church of Jesus Christ, the fel­low­ship of those who hold to “the faith which was once for all hand­ed down to the saints” (Jude 3). ↩
3. We use the term “Catholic” not in ref­er­ence to a denom­i­na­tion, but in its orig­i­nal mean­ing: gen­er­al, uni­ver­sal. There is only one church of Jesus Christ, the fel­low­ship of those who hold to “the faith which was once for all hand­ed down to the saints” (Jude 3). ↩
4. We use the term “Catholic” not in ref­er­ence to a denom­i­na­tion, but in its orig­i­nal mean­ing: gen­er­al, uni­ver­sal. There is only one church of Jesus Christ, the fel­low­ship of those who hold to “the faith which was once for all hand­ed down to the saints” (Jude 3). ↩