Catechism of the Catholic Church §866 — excerpt
The Church is one: she acknowledges one Lord, confesses one faith, is born of one Baptism, forms only one Body, is given life by the one Spirit, for the sake of one hope (cf Eph 4:3-5), at whose fulfillment all divisions will be overcome.
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.