https://www.gty.org/library/articles/A215/our-triune-god
How about the Nicene Crede? That kinda predates the Catholic Church as such.
>We believe in one God, the Father Almighty, Maker of heaven and earth, and of all things visible and invisible. And in one Lord Jesus Christ, the Son of God, the only-begotten, begotten of the Father before all ages. Light of Light; true God of true God; begotten, not made; of one essence with the Father, by whom all things were made; who for us men and for our salvation came down from heaven, and was incarnate of the Holy Spirit and the Virgin Mary, and became man. And He was crucified for us under Pontius Pilate, and suffered, and was buried. And the third day He rose again, according to the Scriptures; and ascended into heaven, and sits at the right hand of the Father; and He shall come again with glory to judge the living and the dead; whose Kingdom shall have no end.