Catechism of the Catholic Church §817 — excerpt
In fact, "in this one and only Church of God from its very beginnings there arose certain rifts, which the Apostle strongly censures as damnable.
This translation is under copyright, so only the cited words are quoted here. Follow the link for the full text. Translation: English translation of the Catechism of the Catholic Church, 2nd ed. (Libreria Editrice Vaticana), as posted at vatican.va.
Also cites: UR 3 # 1 · CIC, can. 751 · Origen, Hom. in Ezech. 9, 1: PG 13, 732