86 The Constitution Lumen Gentium , in a fundamental affirmation echoed by the Decree Unitatis Redintegratio , states that the one Church of Christ subsists in the Catholic Church. The Decree on Ecumenism emphasizes the presence in her of the fullness ( plenitudo ) of the means of salvation. Full unity will come about when all share in the fullness of the means of salvation entrusted by Christ to his Church.
Source: Ut Unum Sint (Vatican.va)