The Athanasian Creed
Whoever wants to be saved should above all cling to the catholic faith. Whoever does not guard it whole and undefiled will doubtless perish eternally.
And 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 the Father is one person, the Son is another, and the Spirit is still another.
But the Godhead of the Father, Son, and Holy Spirit is one, equal in glory, coeternal in majesty.
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 eternal beings, but one who is eternal; as there are not three uncreated and unlimited beings, but one who is uncreated and unlimited.
So likewise the Father is Almighty; the Son Almighty; and the Holy Spirit Almighty. And yet they are not three Almighties; but one Almighty.
So the Father is God; the Son is God; and the Holy Spirit is God. And yet they are not three Gods; but one God.
So likewise the Father is Lord; the Son is Lord; the Holy Spirit is Lord: And yet there are not three lords, but one Lord.
For as Christian truth compels us to acknowledge each distinct person as God and Lord, so catholic religion forbids us to say that there are three Gods or Lords.
The Father was neither made nor 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 the whole three Persons are coeternal, and coequal. So that in all things we must worship the Trinity in unity and the one God in three persons. He therefore that will be saved, let him thus think of the Trinity.
Furthermore, it s necessary for eternal salvation that one also faithfully believe the Incarnation of our Lord Jesus Christ. For this is the true faith 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, with a rational soul and a human body; equal to the Father in divinity, subordinate to the Father in humanity.
Who although he is God and Man; yet he is not two, but one Christ. One; not by conversion of the Godhead into flesh; but by assumption of the Manhood into God.
One altogether; not by confusion of Substance ; but by unity of Person.
For as the rational soul and body is one man; so God and Man is one Christ.
He suffered death for our salvation. He descended into hell and rose again the third day from the dead.
He ascended into heaven and is seated at the right hand of the Father.
He will come again to judge the living and the dead.
At his coming all people shall rise bodily to give an account of their own deeds.
Those who have done good will enter eternal life, those who have done evil will enter eternal fire.
This is the catholic faith.
One cannot be saved without believing this firmly and faithfully.