The true friends of the people are neither revolutionaries, nor innovators, but traditionalists.
Pope Pius XIs 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 XTruly we are passing through disastrous times, when we may well make our own the lamentation of the Prophet: "There is no truth, and there is no mercy, and there is no knowledge of God in the land" (Hosea 4:1). Yet in the midst of this tide of evil, the Virgin Most Merciful rises before our eyes like a rainbow, as the arbiter of peace between God and man.
Pope Pius X