12 But with what bitterness and in how many guises war has been waged against the Church it would be ill-timed now to urge. From the fact that it has been vouchsafed to human reason to snatch from nature, through the investigations of science, many of her treasured secrets and to apply them befittingly to the divers requirements of life, men have become possessed with so arrogant a sense of their own powers as already to consider themselves able to banish from social life the authority and empire of God. Led away by this delusion, they make over to human nature the dominion of which they think God has been despoiled; from nature, they maintain, we must seek the principle and rule of all truth; from nature, they aver, alone spring, and to it should be referred, all the duties that religious feeling prompts. Hence, they deny all revelation from on high, and all fealty due to the Christian teaching of morals as well as all obedience to the Church, and they go so far as to deny her power of making laws and exercising every other kind of right, even disallowing the Church any place among the civil institutions of the commonweal. These men aspire unjustly, and with their might strive, to gain control over public affairs and lay hands on the rudder of the State, in order that the legislation may the more easily be adapted to these principles, and the morals of the people influenced in accordance with them. Whence it comes to pass that in many countries Catholicism is either openly assailed or else secretly interfered with, full impunity being granted to the most pernicious doctrines, while the public profession of Christian truth is shackled oftentimes with manifold constraints.
Source: Sapientiae Christianae (Vatican.va)