1 At the very beginning of our Pontificate, as We reviewed the entire Catholic world, We found much cause for joy in the many and various good works in which the bishops, the secular and religious clergy, and the faithful are constantly engaged. Nevertheless, it grieves Us to think that the enemies of the Church, joined in most wicked conspiracy, scheme to weaken and even, if possible, utterly wipe out that wondrous edifice which God Himself has erected as a refuge for the human race. This combat ardently waged against the Church far and wide, although carried on in different ways for different places, has one established plan: to remove all traces of religion from families, schools, laws, and institutions; to deprive the Church itself of its means of action and that singular virtue it possesses for the common good; and to infiltrate every vein, as it were, of domestic and civil society with the most dangerous poison of their errors. And so these adversaries have left nothing untried; their license has been boundless. In number and with violence, they have assailed the rights, liberty and dignity of the Church; the bishops and all ranks of the clergy; and especially the authority of the Roman Pontiff as well as the Pontiff himself. As a result of these attacks on the Catholic name, grave ills have befallen nations. The enemies extend their perverse views ever more widely, and the immorality and rebellion which accompany such views sweep away souls with the result that greater dangers daily threaten states and governments. Nor was any other result to be expected. Religion is the strongest bulwark of the state. It can, by proper warning and salutary prohibition, hold people fast to their obligations. But when religion is weakened, or worse still, tossed aside, then straightaway the foundations of society waver and are destroyed.
Source: In Ipso (Vatican.va)