Catechism of the Catholic Church §778 — excerpt
The Church is both the means and the goal of God's plan: prefigured in creation, prepared for in the Old Covenant, founded by the words and actions of Jesus Christ, fulfilled by his redeeming cross and his Resurrection, the Church has been manifested as the mystery of salvation by the outpouring of the Holy Spirit.
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.