3 These are fundamental principles: No matter what the Christian does, even in the realm of temporal goods, he cannot ignore the supernatural good. Rather, according to the dictates of Christian philosophy, he must order all things to the ultimate end, namely, the Highest Good. All his actions, insofar as they are morally either good or bad (that is to say, whether they agree or disagree with the natural and divine law), are subject to the judgment and judicial office of the Church. All who glory in the name of Christian, either individually or collectively, if they wish to remain true to their vocation, may not foster enmities and dissensions between the classes of civil society. On the contrary, they must promote mutual concord and charity. The social question and its associated controversies, such as the nature and duration of labor, the wages to be paid, and workingmen's strikes, are not simply economic in character. Therefore they cannot be numbered among those which can be settled apart from ecclesiastical authority. "The precise opposite is the truth. It is first of all moral and religious, and for that reason its solution is to be expected mainly from the moral law and the pronouncements of religion."
Source: Singulari Quadam (Vatican.va)