Although elements of truth and sanctification are found in many churches outside of Catholicism, the Catholic Church is the only one to contain the
fullness of the Christian faith. Vatican II’s
Lumen Gentium (LG) states:
"Christ, the one Mediator, established and continually sustains here on earth His holy Church, the community of faith, hope and charity, as an entity with visible delineation through which He communicated truth and grace to all… This is the one Church of Christ which in the Creed is professed as one, holy, catholic and apostolic, which our Saviour, after His Resurrection, commissioned Peter to shepherd, and him and the other apostles to extend and direct with authority, which He erected for all ages as ‘the pillar and mainstay of the truth’. This Church constituted and organized in the world as a society, subsists in the Catholic Church, which is governed by the successor of Peter and by the Bishops in communion with him..." (LG 8).