St Fulgentius' witness against 'Eastern Orthodox' and neo-Catholics
Early Church Father St Fulgentius rejected an array of contemporary errors back in the sixth century—and affirmed our duty to anathematise those who teach error.

Early Church Father St Fulgentius rejected an array of contemporary errors back in the sixth century—and affirmed our duty to anathematise those who teach error.
Editor’s Notes
The following text is an extract from St Fulgentius of Ruspe’s work De Fide ad Petrum.
Fabius Claudius Gordianus Fulgentius (d. 527/533) was born in North Africa. He was the Bishop of Ruspe in North Africa.
He was a monk, ascetic, distinguished theologian and defender of the Catholic faith. He fought hard against Arianism and Semipelagianism, and was exiled under the Arian King Thrasimund. He used his exile to strengthen the Church through theological writings, including works on predestination, grace, and the Trinity, securing his place as the leading theologian of the sixth century.
His lasting legacy and influence are demonstrated by the definition of the Council of Florence, which closely echoed the words of Chapters 37-39:
It firmly believes, professes and preaches that all those who are outside the catholic church, not only pagans but also Jews or heretics and schismatics, cannot share in eternal life and will go into the everlasting fire which was prepared for the devil and his angels, unless they are joined to the catholic church before the end of their lives; that the unity of the ecclesiastical body is of such importance that only for those who abide in it do the Church’s sacraments contribute to salvation and do fasts, almsgiving and other works of piety and practices of the Christian militia produce eternal rewards; and that nobody can be saved, no matter how much he has given away in alms and even if he has shed his blood in the name of Christ, unless he has persevered in the bosom and the unity of the Catholic Church.1
This Council borrowed other texts from St Fulgentius as well, including Chapter 42 (below).
The Text
St Fulgentius was influenced by St. Augustine. The text which we are sharing has sometimes been attributed to St Augustine himself—hence the occasional references to “Pseudo-Augustine.” It is cast as a reply to a certain Peter (sometimes referred to as “Peter the Deacon”), offering him a summary of the Catholic faith for teaching in Jerusalem.
In the extracts shared, we find St Fulgentius affirming Catholic truths that are questioned today, whether by “Eastern Orthodox” schismatics, “conservative liberals,” or those who wish to defend the claims of the Conciliar/Synodal claimants to the papacy.
The controverted truths which St Fulgentius affirms include:
That the Holy Ghost proceeds from the Father and the Son (Filioque—Chapter XI)
That baptism can be validly administered outside the Church, and should not be (absolutely) repeated when it has been so (Chapter III n. 41, Chapter XXXVI)
That there is absolutely no salvation outside the Church (Chapters XXXVI-XXXVIII)
That heretics and schismatics are outside the Church (Chapter XXXIX)
That “baptism of blood” is a patristic concept, and that some persons can be “within” the Church prior to baptism by “[holding] to the unity of the Catholic Church” – without this applying to every heretic or schismatic “martyr” (Chapter III n. 41)
That everyone can and must recognise that, when someone who denies dogma or teaches doctrines contrary to the Catholic faith is a heretic, who should be rejected and “anathematised by all Catholics” (Chapter XLIV)
The testimony of one saint and Church Father does not settle an argument; St Fulgentius also expresses some other ideas that have certainly been set aside by the Church. But this text certainly bears witness to the prevalence of the above doctrines in the sixth century.
Below are the prologue, the chapter on the Filioque, and the last few chapters of this work.
On the Faith, or On the Rule of the True Faith, to Peter
De Fide, seu de Regula Verae Fidei, ad Petrum
St Fulgentius of Ruspe
From Migne, Tome 65.2
Prologue
1. I have received your letter, my son Peter, a token of your charity, in which you have expressed your intention to journey to Jerusalem and have requested to be instructed by our letters on the rule of true faith which you must hold in those regions, so that no notion of heretical falsehood may stealthily creep upon you.
I rejoice indeed that you show concern for preserving the true faith without any taint of perfidy, for without this concern, conversion can neither be profitable nor even exist. For Apostolic authority declares: “Without faith, it is impossible to please God” (Heb. XI, 6).
Faith is the foundation of all good things. Faith is the beginning of man’s salvation. Without it, no one can belong to the number of the sons of God; for without it, no one in this world attains the grace of justification, nor shall he possess eternal life in the world to come. And if a man does not walk by faith in this life, he shall not attain to vision [in the next].
Without faith, all human labour is in vain. A man who seeks to please God by despising the world, and yet attempts this without true faith, is like one who sets out for his homeland, knowing he shall live there in blessedness, yet abandons the straight path and heedlessly follows error. Thus, he does not reach the blessed city but falls into a precipice, where no joy awaits the traveller, only ruin for the one who stumbles.
The plan for the work
2. Nevertheless, that a sufficient discourse on faith may be set forth, the constraint of time does not permit, since you desire to receive our response quickly, and the magnitude of this inquiry is so great that it can scarcely be fulfilled even with lengthy discussion.
For you have not requested to be instructed in the faith in such a way as to designate some particular heresy against which the focus of our discussion should be specifically directed; rather, since you ask for a general definition of faith and desire that it be expressed succinctly, you clearly see how impossible it is for us to fully comprehend so great a matter in a brief discourse. We are insufficient for the task, even if we had ample time and such intellectual capacity that we could compose many volumes on that which you seek from us.
But since “the Lord is near to all who call upon him in truth” (Ps. CXLIV, 18), and “He will finish his word and cut it short upon the earth” (Rom. IX, 28), I hope that just as hehas given you this holy zeal for the faith, so too will he grant me the ability to serve your most worthy and commendable desire, so that, even if I cannot set forth everything by which every heretical error may be recognised, and once recognised, either refuted or avoided, yet in the name and with the aid of the Holy Trinity, who alone is the one true and good God, I shall state those things in which, at least in great part, the doctrine of the Catholic faith may be established without the smog of error.
By retaining these truths, you will also be able to discern and reject those errors which, even if they are not specifically refuted in this work, nevertheless may be recognised from what is here generally and absolutely set forth—those errors which unfaithful men whisper into the ears of the faithful, not as a rule delivered by divine truth, but as the wicked fabrication of human error.
Baptism is not to be repeated
Chapter III, n. 41
At different times, those whom God has saved freely, without any preceding merit of good will or good works, have attained to that kingdom through the sacraments which Christ instituted for faith in his Incarnation.
And from the time that our Saviour said: “Unless a man be born again of water and the Holy Spirit, he cannot enter into the kingdom of God” (John III, 5), no one can receive the kingdom of heaven or eternal life without the sacrament of baptism—except for those who, within the Catholic Church, pour out their blood for Christ without baptism.
For whether a man receives the sacrament of baptism in the Catholic Church, in any heresy, or in schism, provided that he is baptised in the name of the Father, and of the Son, and of the Holy Spirit, he indeed receives the full sacrament; but he will not have salvation, which is the power of the sacrament, if he possesses the sacrament outside the Catholic Church.
Therefore, he must return to the Church—not in order to receive the sacrament of baptism again (which no one should ever repeat in any person who has already been baptised), but so that he may receive eternal life in the Catholic communion, for which he can never be fit while remaining alienated from the Catholic Church, even though he possesses the sacrament of baptism.
For if a man should give great alms and even shed his blood for the name of Christ, yet in this life has not held to the unity of the Catholic Church, he shall not have eternal salvation.
Where baptism can profit a man, there also can almsgiving be of benefit. However, while baptism may indeed exist outside the Church, it cannot be of any benefit unless within the Church.
The Catholic Church
Chapter III, n. 42
Therefore, only within the Catholic Church can the reception of baptism, works of mercy, and the glorious confession of the name of Christ be of any benefit to a man—provided, however, that he lives rightly within the Catholic Church.
For just as neither baptism nor works of mercy can benefit anyone outside the communion of the Catholic Church—except perhaps so as to mitigate his punishment, though not so as to be counted among the sons of God—so too, within the Catholic Church, eternal life is not attained by baptism alone, if one lives wickedly after baptism.
For even those who live well must persevere unceasingly in works of mercy, knowing that, although their sins may be light, they nonetheless contract some sins daily, for which even the saints and the just must always say to God in this life: “Forgive us our debts, as we also forgive our debtors” (Matt. VI, 12).
And just as such sins frequently creep up on men even in lawful matters and things permitted by God, so too, the more the body is filled with richer foods, and the more the heart of man is entangled in carnal actions and affections, the more frequently guilt is incurred in this mortal life.
The Holy Ghost
Chapter XI, or Rule VIII
32. Hold most firmly, and do not doubt in the least, that the same Holy Ghost, who is the one Spirit of the Father and the Son, proceeds from both the Father and the Son.
For the Son says: “When the Spirit of truth comes, who proceeds from the Father” (John XV, 26); wherein he teaches that the Spirit is his own, because he himself is the Truth (John XIV, 6). That the Holy Ghost also proceeds from the Son is commended to us by both prophetic and apostolic doctrine.
For Isaiah says of the Son: “He shall strike the earth with the rod of his mouth, and with the spirit of his lips shall he slay the wicked” (Isa. XI, 4). Of whom also the Apostle says: “Whom the Lord Jesus shall slay with the spirit of his mouth” (II Thess. II, 8).
The only-begotten Son of God likewise signified that the Spirit is that of his own mouth, for after his resurrection, breathing upon his disciples, he said: “Receive the Holy Ghost” (John XX, 22). And of the very mouth of the Lord Jesus, John says in the Apocalypse that “a sharp two-edged sword proceeded” (Apoc. I, 16).
Thus, this very Spirit of his mouth is himself the sword that proceeds from his mouth.
Baptism
Chapter XXXVI, or Rule XXXIII
77. Hold most firmly, and do not doubt in the least, that the sacrament of baptism can exist not only within the Catholic Church, but also among heretics who baptise in the name of the Father and of the Son and of the Holy Ghost; yet outside the Catholic Church, it cannot be of benefit. Indeed, just as within the Church, baptism confers salvation upon those who rightly believe, so too, to those baptised outside the Church, if they do not return to the Church, the same baptism brings about their destruction (I, quaest. I, cap. Firmissime).
For so great is the efficacy of the unity of ecclesiastical society unto salvation, that one who does not receive baptism in the place where it ought to be given is not saved by it. Nevertheless, baptism remains in a man even if he be baptised outside the Church; but if he remains separated from the Church, it remains "for his condemnation. And since it is manifest that this baptism, wherever it may be given, is to be conferred but once, therefore, even if it has been administered by heretics in the name of the Father and of the Son and of the Holy Ghost, it is to be venerated and in no wise repeated. For the Saviour says: “He that is washed needeth not but to wash his feet” (John XIII, 10).
No salvation outside the Church
Chapter XXXVII, or Rule XXXIV
78. Hold most firmly, and do not doubt in the least, that anyone baptised outside the Catholic Church cannot partake of eternal life, unless before the end of this life he has been restored to the Catholic faith and incorporated into the Church. For the Apostle says: “If I have all faith, and know all mysteries, but have not charity, I am nothing” (1 Cor. XIII, 2). And indeed, in the days of the Flood, we read that no one was saved outside the Ark.
Those who are damned
Chapter XXXVIII, or Rule XXXV
79. Hold most firmly, and do not doubt in the least, that not only all pagans, but also all Jews, and all heretics and schismatics who end their lives outside the Catholic Church shall go into eternal fire, which has been prepared for the devil and his angels (Matt. XXV, 41).
Heretics
Chapter XXXIX, or Rule XXXVI
80. Hold most firmly, and do not doubt in the least, that any heretic or schismatic, even if baptised in the name of the Father and of the Son and of the Holy Ghost, if he has not been united to the Catholic Church, cannot in any way be saved; no matter how many alms he has given, or even if he has shed his blood for the name of Christ.
For to any man who does not hold unity with the Catholic Church, neither baptism, nor almsgiving, however great, nor even death suffered for the name of Christ, can avail for salvation, so long as the heretical or schismatic perversity which leads to death remains in him.
Sinful Christians
Chapter XL, or Rule XXXVII
81. Hold most firmly, and do not doubt in the least, that not all who are baptised within the Catholic Church shall attain eternal life, but only those who, having received baptism, live rightly; that is, who have abstained from vices and the lusts of the flesh. For just as unbelievers, heretics, and schismatics shall not inherit the kingdom of heaven, so too shall criminal Catholics be unable to possess it.
No one lives without sin
Chapter XLI, or Rule XXXVIII
82. Hold most firmly, and do not doubt in the least, that even just and holy men, excepting those who were baptised as infants, cannot live in this world without sin; and that it is always necessary for every man, until the end of this present life, to wash away his sins by almsgiving, fasting, prayer, or tears, and to humbly and sincerely seek remission from God.
The wicked mingled with the good in the Church
Chapter XLIII, or Rule XL
84. Hold most firmly, and do not doubt in the least, that the threshing floor of God is the Catholic Church, and that within it, even to the end of the world, chaff is mingled with the wheat; that is, the wicked are mixed with the good in the communion of the sacraments; and that in every state of life, whether clerics, monks, or laymen, there are both good and evil men. The good must not be abandoned on account of the wicked, but the wicked must be endured for the sake of the good, insofar as the rule of faith and charity demands; that is, provided they neither spread the seeds of perfidy within the Church nor lead their brethren by deadly example to some evil deed.
Nor can anyone believing rightly and living well within the Catholic Church ever be stained by another’s sin, if he gives neither consent nor approval to the sinner; and indeed, the wicked are profitably tolerated within the Church by the good, provided that this is done while living well among them and admonishing them rightly; so that, seeing and hearing what is good, they may reject their own evil, and tremble at the thought of being judged by God for their wicked deeds. Thus, with the prevenient gift of grace, they may be brought to confusion for their iniquities and be converted to a good life through the mercy of God.
However, the good within the Catholic Church ought to be separated from the wicked only by the distinction of their works, so that while they share in the divine sacraments with them, they do not have in common the evil deeds for which they are guilty. Yet, at the end of the world, the good must also be separated bodily from the wicked, when Christ shall come, “having his fan in his hand, and he will thoroughly cleanse his threshing floor, and will gather his wheat into the barn, but the chaff he will burn with unquenchable fire” (Matt. III, 12); when, by his just judgment, he will separate the just from the unjust, the good from the wicked, the upright from the perverse: He will set the good at his right hand and the wicked at his left; and from his mouth, by the eternal and unchanging sentence of his everlasting judgment, “the wicked shall go into everlasting punishment, but the just into life everlasting” (Matt. XXV, 46): the wicked shall burn forever with the devil, but the just shall reign without end with Christ.
Perseverance in the Faith—duty on ‘all Catholics’ to anathematise heretics
Chapter XLIV
85. Faithfully believe, steadfastly hold, and truthfully and patiently defend these forty chapters, which most firmly pertain to the rule of true faith. And if you discover anyone teaching doctrines contrary to them, flee from him as from a plague, and cast him out as a heretic.
For what we have set forth is in full accord with the Catholic faith, so that if anyone seeks to oppose it—not only as a whole but even in a single point—then, inasmuch as he obstinately resists any of these articles and does not hesitate to teach what is contrary to them, he is a heretic and an enemy of the Christian faith, and must therefore be anathematised by all Catholics.
Although, therefore, the urgency of time and the haste of the messenger have compelled us to pass over in silence certain matters which ought to have been included for the recognition and avoidance of various heresies, nonetheless, if you make an effort to review everything contained in this little work and to hold firmly to what is most well-known, you will be able, with prudent discernment, to judge even other matters in a spiritual manner. For the Apostle says: “The spiritual man judgeth all things” (1 Cor. II, 15); and until each of us attains that state, let him walk according to what he has already reached, that is, let him faithfully persevere in what he has certainly received.
But if anyone thinks otherwise, God will also reveal this to him. Amen.
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English base text translated by AI, each line scrutinised by a human.