12 Now, the fundamental doctrine of the naturalists, which they sufficiently make known by their very name, is that human nature and human reason ought in all things to be mistress and guide. Laying this down, they care little for duties to God, or pervert them by erroneous and vague opinions. For they deny that anything has been taught by God; they allow no dogma of religion or truth which cannot be understood by the human intelligence, nor any teacher who ought to be believed by reason of his authority. And since it is the special and exclusive duty of the Catholic Church fully to set forth in words truths divinely received, to teach, besides other divine helps to salvation, the authority of its office, and to defend the same with perfect purity, it is against the Church that the rage and attack of the enemies are principally directed.
Source: Humanum Genus (Vatican.va)