150 years ago: First Vatican Council issues decree proclaiming papal infallibility

On July 18, 1870, the First Vatican Council, which had been convened by Pope Pius IX on June 29, 1868, issued Pastor aeternus (First Dogmatic Constitution on the Church of Christ). Pastor aeternus defined four Roman Catholic doctrines regarding the papacy: I. Of the Institution of the Apostolic Primacy in blessed Peter; II. On the Perpetuity of the Primacy of blessed Peter in the Roman Pontiffs; III. On the Power and Nature of the Primacy of the Roman Pontiff; IV. Concerning the Infallible Teaching of the Roman Pontiff. The doctrine that attracted the most controversy was Chapter IV, the text of which reads:

First Dogmatic Constitution on the Church of Christ.

Published in the Fourth Session of the holy Œcumenical Council of the Vatican.

PIUS BISHOP, SERVANT OF THE SERVANTS OF GOD, WITH THE APPROVAL OF THE SACRED COUNCIL, FOR AN EVERLASTING REMEMBRANCE...

...Chapter IV.
Concerning the Infallible Teaching of the Roman Pontiff.

Moreover, that the supreme power of teaching is also included in the Apostolic primacy, which the Roman Pontiff, as the successor of Peter, Prince of the Apostles, possesses over the whole Church, this Holy See has always held, the perpetual practice of the Church confirms, and œcumenical Councils also have declared, especially those in which the East with the West met in the union of faith and charity. For the Fathers of the Fourth Council of Constantinople, following in the footsteps of their predecessors, gave forth this solemn profession: The first condition of salvation is to keep the rule of the true faith. And because the sentence of our Lord Jesus Christ can not be passed by, who said: 'Thou art Peter, and upon this rock I will build my Church,'301 these things which have been said are approved by events, because in the Apostolic See the Catholic religion and her holy and well-known doctrine has always been kept undefiled. Desiring therefore, not to be in the least degree separated from the faith and doctrine of that See, we hope that we may deserve to be in the one communion, which the Apostolic See preaches, in which is the entire and true solidity of the Christian religion.302

And, with the approval of the Second Council of Lyons, the Greeks professed that the holy Roman Church enjoys supreme and full primacy and preeminence over the whole Catholic Church, which it truly and humbly acknowledges that it has received with the plenitude of power from our Lord himself in the person of blessed Peter, Prince or Head of the Apostles, whose successor the Roman Pontiff is; and as the Apostolic See is bound before all others to defend the truth of faith, so also, if any questions regarding faith shall arise, they must be defined by its judgment.303

Finally, the Council of Florence defined:304 That the Roman Pontiff is the true vicar of Christ, and the head of the whole Church, and the father and teacher of all Christians; and that to him in blessed Peter was delivered by our Lord Jesus Christ the full power of feeding, ruling, and governing the whole Church.305

To satisfy this pastoral duty, our predecessors ever made unwearied efforts that the salutary doctrine of Christ might be propagated among all the nations of the earth, and with equal care watched that it might be preserved genuine and pure where it had been received. Therefore the Bishops of the whole world, now singly, now assembled in Synod, following the long-established custom of churches,306 and the form of the ancient rule,307 sent word to this Apostolic See of those dangers especially which sprang up in matters of faith, that there the losses of faith might be most effectually repaired where the faith can not fail.308 And the Roman Pontiffs, according to the exigencies of times and circumstances, sometimes assembling œcumenical Councils, or asking for the mind of the Church scattered throughout the world, sometimes by particular Synods, sometimes using other helps which Divine Providence supplied, defined as to be held those things which with the help of God they had recognized as conformable with the sacred Scriptures and Apostolic traditions. For the Holy Spirit was not promised to the successors of Peter, that by his revelation they might make known new doctrine; but that by his assistance they might inviolably keep and faithfully expound the revelation or deposit of faith delivered through the Apostles. And, indeed, all the venerable Fathers have embraced, and the holy orthodox doctors have venerated and followed, their Apostolic doctrine; knowing most fully that this See of holy Peter remains ever free from all blemish of error according to the divine promise of the Lord our Saviour made to the Prince of his disciples: 'I have prayed for thee that thy faith fail not, and, when thou art converted, confirm thy brethren.'309

This gift, then, of truth and never-failing faith was conferred by heaven upon Peter and his successors in this chair, that they might perform their high office for the salvation of all; that the whole flock of Christ, kept away by them from the poisonous food of error, might be nourished with the pasture of heavenly doctrine; that the occasion of schism being removed, the whole Church might be kept one, and, resting on its foundation, might stand firm against the gates of hell.
But since in this very age, in which the salutary efficacy of the Apostolic office is most of all required, not a few are found who take away from its authority, we judge it altogether necessary solemnly to assert the prerogative which the only-begotten Son of God vouchsafed to join with the supreme pastoral office.

Therefore faithfully adhering to the tradition received from the beginning of the Christian faith, for the glory of God our Saviour, the exaltation of the Catholic religion, and the salvation of Christian people, the sacred Council approving, we teach and define that it is a dogma divinely revealed: that the Roman Pontiff, when he speaks ex cathedra, that is, when in discharge of the office of pastor and doctor of all Christians, by virtue of his supreme Apostolic authority, he defines a doctrine regarding faith or morals to be held by the universal Church, by the divine assistance promised to him in blessed Peter, is possessed of that infallibility with which the divine Redeemer willed that his Church should be endowed for defining doctrine regarding faith or morals; and that therefore such definitions of the Roman Pontiff are irreformable310 of themselves, and not from the consent of the Church.
But if any one—which may God avert—presume to contradict this our definition: let him be anathema.

Given at Rome in public Session solemnly held in the Vatican Basilica in the year of our Lord one thousand eight hundred and seventy, on the eighteenth day of July, in the twenty-fifth year of our Pontificate.

301 Matt. xvi. 18.

302 From the Formula of St. Hormisdas, subscribed by the Fathers of the Eighth General Council (Fourth of Constantinople), A.D. 869 (Labbe's Councils, Vol. V. pp. 583, 622).

303 From the Acts of the Fourteenth General Council (Second of Lyons), A.D. 1274 (Labbe, Vol. XIV. p. 512).

304 From the Acts of the Seventeenth General Council of Florence, A.D. 1438 (Labbe, Vol. XVIII. p. 526).

305 John xxi. 15-17.

306 From a letter of St. Cyril of Alexandria to Pope St. Celestine I., A.D. 422 (Vol. VI. Part II. p. 36, Paris edition of 1638).

307 From a Rescript of St. Innocent I. to the Council of Milevis, A.D. 402 (Labbe, Vol. III. p. 47).

308 From a letter of St. Bernard to Pope Innocent II. A.D. 1130 (Epist. 191, Vol. IV. p. 433, Paris edition of 1742).

309 Luke xxii. 32. See also the Acts of the Sixth General Council, A.D. 680 (Labbe, Vol. VII. p. 659).

310 That is, in the words used by Pope Nicholas I., note 13, and in the Synod of Quedlinburg, A.D. 1085, 'It is allowed to none to revise its judgment, and to sit in judgment upon what it has judged' (Labbe, Vol. XII. p. 679).

The way the doctrine is defined by the Roman Catholic Church, papal infallibility only once (so far): On November 1, 1950, Pope Pius XII exercised his official infallibility in the apostolic constitution Munificentissimus Deus, which includes:

...3. Actually God, who from all eternity regards Mary with a most favorable and unique affection, has "when the fullness of time came"(2) put the plan of his providence into effect in such a way that all the privileges and prerogatives he had granted to her in his sovereign generosity were to shine forth in her in a kind of perfect harmony. And, although the Church has always recognized this supreme generosity and the perfect harmony of graces and has daily studied them more and more throughout the course of the centuries, still it is in our own age that the privilege of the bodily Assumption into heaven of Mary, the Virgin Mother of God, has certainly shone forth more clearly.

4. That privilege has shone forth in new radiance since our predecessor of immortal memory, Pius IX, solemnly proclaimed the dogma of the loving Mother of God's Immaculate Conception. These two privileges are most closely bound to one another. Christ overcame sin and death by his own death, and one who through Baptism has been born again in a supernatural way has conquered sin and death through the same Christ. Yet, according to the general rule, God does not will to grant to the just the full effect of the victory over death until the end of time has come. And so it is that the bodies of even the just are corrupted after death, and only on the last day will they be joined, each to its own glorious soul.

5. Now God has willed that the Blessed Virgin Mary should be exempted from this general rule. She, by an entirely unique privilege, completely overcame sin by her Immaculate Conception, and as a result she was not subject to the law of remaining in the corruption of the grave, and she did not have to wait until the end of time for the redemption of her body.

6. Thus, when it was solemnly proclaimed that Mary, the Virgin Mother of God, was from the very beginning free from the taint of original sin, the minds of the faithful were filled with a stronger hope that the day might soon come when the dogma of the Virgin Mary's bodily Assumption into heaven would also be defined by the Church's supreme teaching authority...
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2. Gal 4:4.

This reiteration of the Roman Catholic doctrine that Mary was "from the very beginning free from the taint of original sin" is anything but infallible, as it contradicts the plain words of the Bible:

And Mary said, My soul doth magnify the Lord,
And my spirit hath rejoiced in God my Saviour. Luke 1:46-47

Mary wouldn't have rejoiced in God as her Saviour if she had been "free from the taint of original sin," because she wouldn't have needed a saviour. So much for papal infallibility.