St. Gregory the Dialogist on Heterodox Sacraments

Pope St. Gregory the Dialogist ca. 540-604

[Job’s] friends, who, while acting as his counsellors, at the same time inveigh against him, are an express image of heretics, who under shew of giving counsel, are busied in leading astray; and hence they address the blessed Job as though in behalf of the Lord, but yet the Lord does not commend them, that is, because all heretics, while they try to defend, only offend God.  Whence they are plainly told, and that by the same holy man I desire to reason with God; first shewing that ye are forgers of lies, ye are followers of corrupt doctrines. [Job 13, 3.4.]  According to which it appears that these by their erroneous notions stood as a type of heretics, whom the holy man charges with adhering to a creed [cultui] of corrupt doctrines.  But every heretic, in this, that he is seen to defend God, is a gainsayer of His truth, according to the testimony of the Psalmist, who says, That Thou mightest still the enemy and the defender [Ps. 8, 2. E.V. avenger], for he is an enemy and defender, who so preaches God as thereby to be fighting against Him.
Now because it sometimes happens that heretics being penetrated with the bountiful streams of Divine grace return to the unity of Holy Church, this is well represented in the very reconcilement of his friends.  Yet blessed Job is bidden to intercede for them, because the sacrifices of heretics can never be acceptable to God, unless they be offered in their behalf by the hands of the universal Church, that by her merits they may obtain the recovery of salvation, whom they did strike before by assailing her with the darts of their words; and hence seven sacrifices are recorded to have been offered for them, for whereas in confessing they receive the Spirit of sevenfold grace, they do as it were obtain expiation by seven offerings.  It is hence that in the Apocalypse of John the whole Church is represented by the number of seven Churches [Rev. 1, 12].  Hence it is said of wisdom by Solomon, Wisdom hath builded her house; she hath hewn, out her seven pillars. [Prov. 9, 1] And thus by the very number of the sacrifices those reconciled heretics set forth what they were before, in that these are not united to the perfection of sevenfold grace, except by returning.

But they are well described as having offered for themselves bulls and rams.  For in the bull is figured the neck of pride, and in the ram, the leading of the flocks that follow.  What then is it to slaughter bulls and rams in their behalf, but to put an end to their proud leading, so that they may think humbly of themselves, and not seduce the hearts of the innocent to follow after them.  For they had started away from the unity of the Church with a swelling neck, and were drawing after them the weak folk like flocks following behind.  Therefore let them come to blessed Job; i.e.  return to the Church; and present bulls and rams to be slaughtered for a sevenfold sacrifice, and that they may be united to the universal Church, let them with the interposition of humility kill all the swelling humor wherewith their proud leadership savoured them. (Morals on the Book of Job, Preface: 15, 17-18)

And indeed we have learned from the ancient institution of the Fathers that whosoever among heretics are baptized in the name of the Trinity, when they return to holy Church, may be recalled to the bosom of mother Church either by unction of chrism, or by imposition of hands, or by profession of the faith only. Hence the West reconciles Arians to the holy Catholic Church by imposition of hands, but the East by the unction of holy chrism. But Monophysites and others are received by a true confession only, because holy baptism, which they have received among heretics, then acquires in them the power of cleansing, when either the former receive the Holy Spirit by imposition of hands, or the latter are united to the bowels of the holy and universal Church by reason of their confession of the true faith. Those heretics, however, who are not baptized in the name of the Trinity, such as the Bonosiaci and the Cataphrygæ, because the former do not believe in Christ the Lord, and the latter with a perverse understanding believe a certain bad man, Montanus, to be the Holy Spirit, like whom are many others—these, when they come to holy Church, are baptized, because what they received while in their error, not being in the name of the HolyTrinity, was not baptism. Nor can this be called an iteration of baptism, which, as has been said, had not been given in the name of the Trinity. But the Nestorians, since they are baptized in the name of the Holy Trinity— though darkened by the error of their heresy in that, after the manner of Jewish unbelief, they believe not the Incarnation of the Only-begotten— when they come to the Holy Catholic Church, are to be taught, by firm holding and profession of the true faith, to believe in one and the same Son of God and man, ourLord God Jesus Christ, the same existing in Divinity before the ages, and the same made man in the end of the ages, because The Word was made flesh and dwelt among us Jn. 1:14.(Epistles, Bk. 11: Epistle 67)