25 The priest, raised above all men in order to accomplish the mission he has from God, must also remain above all human interests, all conflicts, all classes of society. His proper field of action is the Church. There, as ambassador of God, he preaches the truth, teaching along with respect for the rights of God respect also for the rights of every creature. In such a work he neither exposes himself to any opposition nor appears as a man of factions, ally to one group and adversary to others. In such a way he will not place himself in the danger of dissimulating the truth, of keeping silence in the conflict of certain tendencies, or of irritating exasperated souls by repeated arguments. In all these cases he would fail in his real duty. It is unnecessary to add that while treating so often of material affairs he may find himself obligated to perform tasks harmful to himself and to the dignity of his office. He may take part in these associations, therefore, only after mature deliberation, with the consent of his Bishop, and then only in those cases when his assistance will be free from every danger and will be obviously useful.
Source: Il Fermo Proposito (Vatican.va)