Catechism of the Catholic Church §775 — excerpt
"The Church, in Christ, is like a sacrament - a sign and instrument, that is, of communion with God and of unity among all men."
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: LG 1