The Athanasian Creed (Quicunque vult)

THE Catholic Faith is this: 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: and another of the Holy Ghost. But the Godhead of the Father, of the Son, and of the Holy Ghost, is all one: the Glory equal, the Majesty co-eternal. Such as the Father is, such is the Son: and such is the Holy Ghost.

The Father uncreate, the Son uncreate: and the Holy Ghost uncreate. The Father incomprehensible, the Son incomprehensible: and the Holy Ghost incomprehensible. The Father eternal, the Son eternal: and the Holy Ghost eternal. And yet there are not three eternals: but one eternal. As also there are not three incomprehensibles, nor three uncreated: but one uncreated and one incomprehensible.

So likewise the Father is Almighty, the Son Almighty: and the Holy Ghost Almighty. And yet there are not three Almighties: but one Almighty. So the Father is God, the Son is God: and the Holy Ghost is God. And yet there are not three Gods: but one God.

So likewise the Father is Lord, the Son Lord: and the Holy Ghost Lord. And yet not three Lords: but one Lord. For like as we are compelled by the Christian verity: to acknowledge every Person by himself to be God and Lord; So are we forbidden by the Catholick 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 Ghost is of the Father and of the Son: neither made, nor created, nor begotten, but proceeding. 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 before or after other: none is greater, or less than another; But the whole three Persons are co-eternal together: and co-equal. So that in all things, as is aforesaid: the Unity in Trinity, and the Trinity in Unity is to be worshiped.

Furthermore, it is necessary to everlasting salvation: that he also believe rightly the Incarnation of our Lord Jesus Christ. For the right Faith is, that we believe and confess: that our Lord Jesus Christ, the Son of God, is God and Man; God, of the Substance of the Father, begotten before the worlds: and Man, of the substance of His Mother, born in the world; Perfect God and perfect Man: of a reasonable soul and human flesh subsisting; Equal to the Father, as touching his Godhead: and inferior to the Father, as touching His Manhood; Who although He be God and Man: yet He is not two, but one Christ; One; not by conversion of the Godhead into flesh: but by taking of the Manhood into God; One altogether; not by confusion of Substance: but by unity of Person.

For as the reasonable soul and flesh is one man: so God and Man is one Christ; Who suffered for our salvation: descended into hell; rose again the third day from the dead; He ascended into heaven, he sitteth on the right hand of the Father, God Almighty: from whence He shall come to judge the quick and the dead. At whose coming all men shall rise again with their bodies: and shall give an account of their own works. And they that have done good shall go into life everlasting: and they that have done evil, into everlasting fire.

This is the Catholic Faith: which except a man believe faithfully, he cannot be saved.