For those that falsely claim that Montini did not abrogate the TLM:
If Montini was pope, he 100% had right to do this. Good thing is that he was not the pope.
…[T]here are those who, under the pretext of a greater fidelity to the Church and the Magisterium, systematically refuse the teaching of the Council itself, its application and the reforms that stem from it, its gradual application by the Apostolic See and the Episcopal Conferences, under our authority, willed by Christ. Discredit is cast upon the authority of the Church in the name of a Tradition, to which respect is professed only materially and verbally. The faithful are drawn away from the bonds of obedience to the See of Peter and to their rightful Bishops; today’s authority is rejected in the name of yesterday’s. And the fact is all the more serious in that the opposition of which we are speaking is not only encouraged by some priests, but is led by a Prelate, Archbishop Marcel Lefebvre, who nevertheless still has our respect.
It is so painful to take note of this; but how can we not see in such an attitude—whatever may be these people’s intentions—the placing of themselves outside obedience and communion with the Successor of Peter and therefore outside the Church?
For this, unfortunately, is the logical consequence, when, that is, it is held as preferable to disobey with the pretext of preserving one’s faith intact, and of working in one’s way for the preservation of the Catholic Church, while at the same time refusing to give her effective obedience. And this is said openly! It is even affirmed that the Second Vatican Council is not binding; that the faith would also be in danger because of the reforms and post-conciliar directives, that one has the duty to disobey in order to preserve certain traditions. What traditions? Is it for this group [=Lefebvrists], not the Pope, not the College of Bishops, not the Ecuмenical Council, to decide which among the innumerable traditions must be considered as the norm of faith? As you see, Venerable Brothers, such an attitude sets itself up as a judge of that divine will which placed Peter and his lawful Successors at the head of the Church to confirm the brethren in the faith, and to feed the universal flock (cf. Lk 22:32; Jn 21:15 ff.), and which established him as the guarantor and custodian of the deposit of faith.
And this is all the more serious, in particular, when division is introduced precisely where congregavit nos in unum Christi amor [the love of Christ has gathered us into one], in the Liturgy and the Eucharistic Sacrifice, by the refusing of obedience to the norms laid down in the liturgical sphere. It is in the name of Tradition that we ask all our sons and daughters, all the Catholic communities, to celebrate with dignity and fervor the renewed liturgy. The adoption of the new Ordo Missae [order of the Mass] is certainly not left to the free choice of priests or faithful. The instruction of 14 June 1971 has provided for, with the authorization of the Ordinary, the celebration of the Mass in the old form only by aged and infirm priests, who offer the divine Sacrifice sine popolo [without people attending]. The new Ordo was promulgated to take the place of the old, after mature deliberation, following upon the requests of the Second Vatican Council. In no different way did our holy Predecessor Pius V make obligatory the Missal reformed under his authority, following the Council of Trent.
With the same supreme authority that comes from Christ Jesus, we call for the same obedience to all the other liturgical, disciplinary and pastoral reforms which have matured in these years in the implementation of the Council decrees. Any initiative which tries to obstruct them cannot claim the prerogative of rendering a service to the Church; in fact it causes the Church serious damage.
Various times, directly and through our collaborators and other friendly persons, we have called the attention of Archbishop Lefebvre to the seriousness of his behaviour, the irregularity of his principal present initiatives, the inconsistency and often falsity of the doctrinal positions on which he bases this behaviour and these initiatives, and the damage that accrues to the entire Church because of them.
It is with profound sadness but with paternal hope that we once more turn to this confrère of ours, to his collaborators and to those who have let themselves be carried away by them. Oh, certainly, we believe that many of these faithful—at least in the beginning—were in good faith: we also understand their sentimental attachment to habitual forms of worship or of discipline that for a long time had been for them a spiritual support and in which they had found spiritual sustenance. But we are confident that they will reflect with serenity, without closed minds, and they will admit that they can find today the support and sustenance that they are seeking in the renewed forms that the Second Vatican Ecuмenical Council and we ourself have decreed as being necessary for the good of the Church, her progress in the modern world, and her unity. We therefore exhort yet once again all these brethren and sons and daughters of ours; we beseech them to become aware of the profound wounds that they otherwise cause to the Church, and we invite them again to reflect on Christ’s serious warnings about the unity of the Church (cf. Jn 17:21 ff) and on the obedience that is due to the lawful Pastor placed by him over the universal flock, as a sign of the obedience due to the Father and to the Son (cf. Lk 10:16). We await them with an open heart, with arms ready to embrace them; may they know how to rediscover in humility and edification, to the joy of the whole People of God, the way of unity and of love!
(Antipope Paul VI, Allocution to the Consistory, May 24, 1976; Translation from L’Osservatore Romano, June 3, 1976.