Against Radical Traditionalism: "Tribus Circiter" (1906) - Pope St Pius X

Full encyclical text here: https://www.vatican.va/content/pius-x/en/encyclicals/documents/hf_p-x_enc_05041906_tribus-circiter.html

[T]his Apostolic See was duly informed that some priests, especially among the junior clergy of your dioceses, had founded...a kind of...society...the members of which, little by little, turned aside from the right road and from the obedience they owe the Bishops "whom the Holy Ghost has placed to rule the Church of God,"[.]

To a certain [individual], whom they proclaimed to be most holy, ...divinely enlightened about many things, and providentially given for the salvation of a world about to perish, they did not hesitate to entrust themselves without reserve[.]

Relying on an alleged mandate from God, they set themselves to promote without discrimination and of their own initiative among the people frequent exercises of piety (highly commendable when rightly carried out,) especially the adoration of the Most Holy Sacrament and the practice of frequent communion; but at the same time they made the gravest charges against all priests and bishops who ventured to express any doubt about the sanctity and divine election of [their leader], or showed any hostility to [their] society[.] Such a pass did matters reach that there was reason to fear that many of the faithful in their delusion were about to abandon their lawful pastors.

Hence, on the advice of Our Venerable Brethren the Cardinals of the General Inquisition, We had a decree issued, as you are aware, under date of September 4, 1904, suppressing the above-named society of priests, and commanding them to break off absolutely all relations with [their leader]. But the priests in question, notwithstanding that they signed a document expressing their subjection to the authority of their bishops...still failed to abandon their undertaking and to renounce sincerely the condemned association. Not only did they condemn your exhortations and inhibitions, not only did many of them sign as audacious declaration in which they rejected communion with their bishops, not only in more places than one did they incite the deluded people to drive away their lawful pastors, but, like the enemies of the Church, asserted that she has fallen from truth and justice, and hence has been abandoned by the Holy Spirit, and that to themselves alone...was it divinely given to instruct the faithful in true piety.

But their profession of fidelity to the Vicar of Christ is vain in those who, in fact, do not cease to violate the authority of their Bishops. For "by far the most august part of the Church consists of the Bishops, (as Our Predecessor Leo XIII of holy memory wrote in his letter of December 17, 1888, to the Archbishop), inasmuch as this part by divine right teaches and rules men; hence, whoever resists them or pertinaciously refuses obedience to them puts himself apart from the Church. . . On the other hand, to pass judgment upon or to rebuke the acts of Bishops does not at all belong to private individuals - that comes within the province only of those higher than they in authority and especially of the Sovereign Pontiff, for to him Christ entrusted the charge of feeding not only His lambs, but His sheep throughout the world. At most, it is allowed in matters of grave complaint to refer the whole case to the Roman Pontiff, and this with prudence and moderation as zeal for the common good requires, not clamorously or abusively, for in this way dissensions and hostilities are bred, or certainly increased."

Wherefore, that the faithful of Christ and all the...priests who are in good faith may no longer be led astray by the [group's] delusions, ...We again confirm the decree whereby the society...is entirely suppressed, and We declare it suppressed and condemned[.]