40 Others oppose not the existence of the Church, nor indeed could they; yet they despoil her of the nature and rights of a perfect society, and maintain that it does not belong to her to legislate, to judge, or to punish, but only to exhort, to advise, and to rule her subjects in accordance with their own consent and will. By such opinion they pervert the nature of this divine society, and attenuate and narrow its authority, its office of teacher, and its whole efficiency; and at the same time they aggrandize the power of the civil government to such extent as to subject the Church of God to the empire and sway of the State, like any voluntary association of citizens. To refute completely such teaching, the arguments often used by the defenders of Christianity, and set forth by Us, especially in the encyclical letter Immortale Dei ,(12) are of great avail; for by those arguments it is proved that, by a divine provision, all the rights which essentially belong to a society that is legitimate, supreme, and perfect in all its parts exist in the Church.
Source: Libertas (Vatican.va)