Whoever will be saved shall, above all else, hold the catholic faith. Which faith, except it be kept whole and undefiled, without doubt, one will perish eternally. And the true Christian faith is this, that we worship one God in Trinity and Trinity in Unity, neither confusing the Persons nor dividing the substance.
For there is one Person of the Father, another of the Son, and another of the Holy Spirit. But the Godhead of the Father, of the Son, and of the Holy Spirit is all 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 there are not three eternals, but one eternal; just as there are not three uncreated, nor three infinites, but one uncreated and one infinite.
Likewise the Father is almighty, the Son is almighty, and the Holy Spirit is almighty. And yet there are not three almighties, but one almighty. So the Father is God, the Son is God, and the Holy Spirit is God. And yet there are not three gods, but one God. Likewise the Father is Lord, the Son is Lord, and the Holy Spirit is Lord. And yet there are not three lords, but one Lord.
For as we are compelled by the Christian truth to acknowledge every Person by Himself to be both God and Lord, so we are forbidden by the true Christian faith to say that there are 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 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 Spirit, not three holy spirits.
And in this Trinity none is before or after another; none is greater or less than another; but all three Persons are coeternal together and coequal, so that in all things, as said before, the Unity in Trinity and the Trinity in Unity is to be worshiped. Whoever will be saved is compelled thus to think of the Holy Trinity.
Furthermore it is necessary for everlasting salvation that one also believe faithfully 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 rational 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 is God and Man, yet He is not two but one Christ; One not by changing of the Godhead into flesh, but by taking the manhood into God; One indeed, not by confusion of substance, but by oneness of person. For just as the rational 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 is seated at the right hand of the Father, God almighty, from there He shall come to judge the living and the dead. At whose coming all will rise again with their bodies and will give an account of their own works. And they that have done good will enter into life everlasting; and they that have done evil into everlasting fire. This is the catholic faith; whoever does not faithfully and firmly believe this cannot be saved.
For those who are interested click below for the Latin Received Text of the Athanasian Creed.