The Athanasian Creed

Whosoever would be saved needeth before all things to hold fast the Catholic Faith. Which Faith except a man keep whole and undefiled, without doubt he will perish eternally.

Now the Catholic Faith is this: That we worship one God in Trinity, and the Trinity in Unity, neither confusing the Persons nor dividing the Substance. For there is one Person of the Father, another of the Son, 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 coeternal. Such as the Father is, such is the Son, and such is the Holy Ghost. The Father uncreated [or incomprehensible], the Son uncreated, the Holy Ghost uncreated. The Father infinite, the Son infinite, the Holy Ghost infinite. The Father eternal, the Son eternal, the Holy Ghost eternal. And yet there are not three eternals, but one eternal. As also there are not three uncreated, nor three infinites, but one infinite, and one uncreated. So likewise the Father is Almighty, the Son Almighty, and the Holy Ghost Almighty. And there are not three Almighties, but one Almighty. So the Father is God, the Son God, the Holy Ghost God. And yet there are not three Gods, but one God. So the Father is Lord, the Son Lord, the Holy Ghost Lord. And yet there are not three Lords, but one Lord. For like as we are compelled by the Christian verity to confess each Person by himself to be both God and Lord, so we are forbidden by the Catholic Religion to speak of three Gods or three Lords. The Father is made of none, nor created, nor begotten. The Son is of the Father alone, not made, nor created, but begotten. The Holy Ghost is of the Father and the Son, not made, nor created, nor begotten, but proceeding. There is therefore one Father, not three Fathers; one Son, not three Sons; one Holy Ghost, not three Holy Ghosts. And in this Trinity there is no before or after, no greater or less; but all three Persons are coeternal together, and coequal. So that in all ways, as is aforesaid, both the Trinity is to be worshipped in Unity, and the Unity in Trinity. He therefore that would be saved, let him thus think of the Trinity.

Furthermore it is necessary to eternal salvation that he also believe faithfully the Incarnation of our Lord Jesus Christ. Now the right Faith 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 all worlds; and he is Man, of the substance of his Mother, born in the world; Perfect God; Perfect Man, of reasoning soul and human flesh subsisting; equal to the Father, as touching his Godhead; less than the Father, as touching his Manhood. Who although he be God and Man, yet is not two, but one Christ; One, however, not by conversion of Godhead into flesh, but by taking of Manhood into God; One altogether, not by confusion of Substance, but by unity of Person. For as reasoning soul and flesh is one man, so God and Man is one Christ; who suffered for our salvation, descended into hell, rose again from the dead, ascended into heaven, sat down at the right hand of the Father, from whence he shall come to judge the quick and the dead. At whose coming all men must rise again with their bodies and shall give account for their own deeds. And they that have done good will go into life eternal; they that have done evil into eternal fire.

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