The Creed "Quicumque"

compelled by Christian truth to confess singly each one person as God and [and also] Lord, so we are forbidden by the Catholic religion to say there are three gods or lords. The Father was not made nor created nor begotten by anyone. 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. There is therefore one Father, not three Fathers; one Son, not three Sons; one Holy Spirit, not three Holy Spirits; and in this Trinity there is nothing first or later, nothing greater or less, but all three persons are coeternal and coequal with one another, so that in every respect, as has already been said above, both unity in Trinity, and Trinity in unity must be venerated. Therefore let him who wishes to be saved, think thus concerning the Trinity.

40. But it is necessary for eternal salvation that he faithfully believe also the incarnation of our Lord Jesus Christ. Accordingly it is the right faith, that we believe and confess, that our Lord Jesus Christ, the Son of God is God and man. He is God begotten of the substance of the Father before time, and he is man born of the substance of his mother in time: perfect God, perfect man, consisting of a rational soul and a human body, equal to the Father according to his Godhead, less than the Father according to humanity. Although he is God and man, yet he is not two, but he is one Christ; one, however, not by the conversion of the Divinity into a human body, but by the assumption of humanity in the Godhead; one absolutely not by confusion of substance, but by unity of person. For just as the rational soul and body are one man, so God and man are one Christ. He suffered for our salvation, descended into hell, on the third day arose again from the dead, ascended to heaven, sits at the right hand of God the Father almighty; thence he shall come to judge the living and the dead; at his coming all men have to arise again with their bodies and will render an account of their own deeds: and those who have done good, will go into life everlasting, but those who have done evil, into eternal fire.—This is the Catholic faith; unless every one believes this faithfully and firmly, he cannot be saved.