100 And yet, Venerable Brethren, the teaching of Christ, which alone can furnish man with such solid bases of belief as will greatly enlarge his vision, and divinely dilate his heart and supply an efficacious remedy to the very grave difficulties of today - this and the activity of the Church in teaching and spreading that Doctrine, and in forming and modeling men's minds by its precepts, are at times an object of suspicion, as if they shook the foundations of civil authority or usurped its rights.
Source: Summi Pontificatus (Vatican.va)