IN BRIEF
"The sole Church of Christ which in the Creed we profess to be one, holy, catholic, and apostolic, . . . Subsists in the Catholic Church, which is governed by the successor of Peter and by the bishops in communion with him. Nevertheless, many elements of sanctification and of truth are found outside its visible confines"(LG 8).
Source: Catechism of the Catholic Church (Vatican.va)