83 For true though it is that the evils from which mankind suffers today come in part from economic instability and from the struggle of interests regarding a more equal distribution of the goods which God has given man as a means of sustenance and progress, it is not less true that their root is deeper and more intrinsic, belonging to the sphere of religious belief and moral convictions which have been perverted by the progressive alienation of the peoples from that unity of doctrine, faith, customs and morals which once was promoted by the tireless and beneficent work of the Church. If it is to have any effect, the reeducation of mankind must be, above all things, spiritual and religious. Hence, it must proceed from Christ as from its indispensable foundation; must be actuated by justice and crowned by charity.
Source: Summi Pontificatus (Vatican.va)