Ut Unum Sint §37

³⁷ The Decree Unitatis Redintegratio also indicates a criterion to be followed when Catholics are presenting or comparing doctrines: "They should remember that in Catholic teaching there exists an order or 'hierarchy' of truths, since they vary in their relationship to the foundation of the Christian faith. Thus the way will be opened for this kind of fraternal rivalry to incite all to a deeper realization and a clearer expression of the unfathomable riches of Christ".