41 If we stop to reflect for a moment that these ideals and doctrines of Jesus Christ, for example, his teachings on the necessity and value of the spiritual life, on the dignity and sanctity of human life, on the duty of obedience, on the divine basis of human government, on the sacramental character of matrimony and by consequence the sanctity of family life - if we stop to reflect, let Us repeat, that these ideals and doctrines of Christ (which are in fact but a portion of the treasury of truth which He left to mankind) were confided by Him to His Church and to her alone for safekeeping, and that He has promised that His aid will never fail her at any time for she is the infallible teacher of His doctrines in every century and before all nations, there is no one who cannot clearly see what a singularly important role the Catholic Church is able to play, and is even called upon to assume, in providing a remedy for the ills which afflict the world today and in leading mankind toward a universal peace.
Source: Ubi Arcano Dei Consilio (Vatican.va)