Is it permitted for Catholics to be present at, or to take part in, conventions, gatherings, meetings, or societies of non-Catholics which aim to associate together under a single agreement everyone who, in any way, lays claim to the name of Christian? In the negative! ... It is clear, therefore, why this Apostolic See has never allowed its subjects to take part in the assemblies of non-Catholics. There is one way in which the unity of Christians may be fostered, and that is by furthering the return to the one true Church of Christ for those who are separated from Her.
Pope Pius XGod being infinite beauty, the soul united to Christ draws upon himself the admiring and tender gaze of the Angels, who, were they capable of any passion, would be filled with envy at his lot.
Pope Pius XThe true friends of the people are neither revolutionaries, nor innovators, but traditionalists.
Pope Pius X