I’ve come to believe that since God possesses the primary Infallibility, and this became manifest in the Word of Christ, it would follow that when Christ spoke again in the New Advent, He would gather all things under the authority of that same Word. Bahá’ís accept that this Word has been spoken again, almost in our own time.
Count Mastai-Ferretti, Bishop of Imola, the 254th pope since the inception of St. Peter’s primacy, who had been elevated to the apostolic throne two years after the Declaration of the Báb, and the duration of whose pontificate exceeded that of any of his predecessors, will be permanently remembered as the author of the Bull which declared the Immaculate Conception of the Blessed Virgin (1854), referred to in the Kitáb-i-Íqán, to be a doctrine of the Church, and as the promulgator of the new dogma of Papal Infallibility (1870)…
This temporal power had, throughout the ages, shrunk to insignificant proportions. The decades preceding its extinction were fraught with the gravest vicissitudes. As the sun of Bahá’u’lláh’s Revelation was mounting to full meridian splendor, the shadows that beset the dwindling patrimony of St. Peter were correspondingly deepening. The Tablet of Bahá’u’lláh, addressed to Pius IX, precipitated its extinction.
In 1870, after Bahá’u’lláh had revealed His Epistle to Pius IX, (full text here
reference.bahai.org/en/t/b/SLH/slh-5.html ) King Victor Emmanuel II went to war with the Papal states, and his troops entered Rome and seized it. On the eve of its seizure, the Pope repaired to the Lateran and, despite his age and with his face bathed in tears, ascended on bended knees the Scala Santa. The following morning, as the cannonade began, he ordered the white flag to be hoisted above the dome of St. Peter. Despoiled, he refused to recognize this “creation of revolution,” excommunicated the invaders of his states, denounced Victor Emmanuel as the “robber King” and as “forgetful of every religious principle, despising every right, trampling upon every law.” Rome, “the Eternal City, on which rest twenty-five centuries of glory,” and over which the Popes had ruled in unchallengeable right for ten centuries, finally became the seat of the new kingdom, and the scene of that humiliation which Bahá’u’lláh had anticipated and which the Prisoner of the Vatican had imposed upon himself. (Shoghi Effendi, Guardian of the Bahá’í Faith 1921-1957,
The Promised Day is Come, p. 53)
**Praise be unto God Who hath made the Most Great Infallibility the shield for the temple of His Cause in the realm of creation, and hath assigned unto no one a share of this lofty and sublime station – a station which is a vesture which the fingers of transcendent power have woven for His august Self. It befitteth no one except Him Who is seated upon the mighty throne of ‘He doeth what He pleaseth’. Whoso accepteth and recognizeth that which is written down at this moment by the Pen of Glory is indeed reckoned in the Book of God, the Lord of the beginning and the end, among the exponents of divine unity, they that uphold the concept of the oneness of God.~**Ishraqat, (Splendours)
Tablets of Baha’u’llah, p. 105)