12 Wherefore, We exhort all, private individuals as well as states, in the Lord, that now when such grave matters are agitated, critical questions concerning the welfare of all mankind, to lay aside that sordid and selfish regard for nothing but their own advantage, which blunts even the keenest minds, and cuts short even the noblest enterprises if they go the least bit beyond the narrow bounds of self-interest. Let all, then, join together, if need be even at the cost of serious loss, so that they may save themselves and all human society. In this union of minds and of forces, those who glory in the Christian name ought surely to take the foremost place, remembering the illustrious examples of the Apostolic age, when "the multitude of believers had but one heart and one soul" ( Acts iv. 32). but besides these, all whoever sincerely acknowledge God and honor Him from their heart should lend their aid in order that mankind may be saved from the great peril impending over all. For since all human authority must needs rest on the recognition of God, as on the firm foundation of any civil order, those who would not have all things overturned and all laws abrogated, must strive strenuously to prevent the enemies of religion from giving effect to the plans which they have so openly and so vehemently proclaimed.
Source: Caritate Christi Compulsi (Vatican.va)