Whosoever wishes to be saved before all things it is necessary that he hold the catholic faith, which faith, if anyone does not keep it whole and unharmed, without doubt he will perish everlastingly.
Now, the catholic faith is this, that we worship one God in Trinity, and Trinity in Unity, neither confusing the Persons nor dividing the divine Being.
For there is one Person of the Father, another of the Son, and another of the Holy Spirit, but the Godhead of the Father, the Son and the Holy Spirit is all one, their glory equal, their majesty co-eternal.
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 they are not three Eternals but one Eternal, just as they are not three Uncreateds, nor three Infinites, but one Uncreated and one Infinite.
In the same way, the Father is almighty, the Son almighty and the Holy Spirit almighty; and yet they are not three Almighties but one Almighty.
Thus the Father is God, the Son is God and the Holy Spirit is God; and yet there are not three Gods but one God.
Thus the Father is the Lord, the Son is the Lord and the Holy Spirit is the Lord; and yet not three Lords but one Lord.
Because, just as we are compelled by Christian truth to confess each Person singly to be both God and Lord, so are we forbidden by the catholic religion to say, There are three Gods, or three Lords.
The Father is from none, not made nor created nor begotten; the Son is from the Father alone, not made nor created, but begotten: the Holy Spirit is from 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; one Holy Spirit, not three Holy Spirits. And in this Trinity there is no before or after, no greater or less, but all three Persons are co-eternal with each other and co-equal.
So that in all things, as has already been said, the Trinity in Unity, and Unity in Trinity, is to be worshipped. He therefore who wishes to be saved let him think thus of the Trinity.
Furthermore, it is necessary to everlasting salvation that he should faithfully believe the incarnation of our Lord Jesus Christ.
Now, the right faith is that we should believe and confess that our Lord Jesus Christ, the Son of God, is both God and man equally.
He is God from the Being of the Father, begotten before the worlds, and he is man from the being of his mother, born in the world; perfect God and perfect man, having both man's rational soul and human flesh; equal to the Father as regards his divinity and inferior to the Father as regards his humanity; who, although he is God and man, yet he is not two, but one Christ; one, however, not by conversion of the Godhead into flesh but by the taking up of humanity into God; utterly one, not by confusion of human and divine being but by unity of Christ's one Person.
For just as the rational soul and flesh are one man, so God and man are one Christ; who suffered for our salvation, descended to Sheol, rose from the dead, ascended to heaven, sat down at the right hand of the Father, from where he will come to judge the living and the dead; at whose coming all men will rise again with their bodies and will give an account for their own actions, and those who have done good will go into life everlasting and those who have done evil into everlasting fire.
This is the catholic faith which, if anyone does not believe it faithfully and firmly, he cannot be saved.
For more info on this creed visit the Church Society website.