The Western Anti-Arian Struggle

Ambrose was the decisive Western champion of the Council of Nicaea at the moment the Latin church’s allegiance still hung in the balance. This file sets out the doctrinal struggle: the inheritance of a Homoian Milan, the five books of De Fide written for the emperor Gratian on the eve of the Gothic war, the Council of Aquileia of 381 that Ambrose orchestrated to depose the Illyrian Arian bishops Palladius and Secundianus, and the relationship of the Western effort to the First Council of Constantinople — the Second Ecumenical Council — meeting in the East in the same year.

Tradition: Pan-Orthodox (Church Father / Latin)

The Stakes in the West

By the time Ambrose became bishop the Arian crisis was two generations old, but it was not over, and in the Latin West its outcome was genuinely undecided. The Council of Nicaea (325) had confessed the Son to be homoousios — of one essence — with the Father; but the decades under Constantius II had imposed, by imperial pressure, a succession of compromise creeds, and the dominant party in the West that Ambrose confronted was the Homoian (“Arian” in the broad polemical sense): those who confessed the Son merely “like” (homoios) the Father, refusing the Nicene homoousios and holding the Son in some sense inferior and subordinate (Williams, Ambrose of Milan, 1–37; see Orthodoxy Guide: The Ecumenical Councils).

Milan itself had been a Homoian see for two decades under Auxentius (see The Man and the See), and the party retained the patronage of the court and a strong base in the Danubian provinces of Illyricum. The Nicene cause in the West needed an articulate, well-connected champion. The accident of Ambrose’s election had supplied one — though it would take him some years of study to become it (see From Governor to Bishop).

The Homoian ascendancy Ambrose inherited was the fruit of a deliberate imperial settlement a generation old. Under Constantius II, sole emperor after 353, a series of councils labored to replace the Nicene homoousios with formulas acceptable to the broad anti-Nicene coalition. The decisive instrument was the “Dated Creed” of Sirmium (the Fourth Sirmian Formula, 22 May 359), confessing the Son “like the Father in all things,” and the parallel councils of Rimini (Ariminum) in the West and Seleucia in the East later that year, where the assembled bishops — worn down, isolated, and pressed by the imperial commissioners — subscribed a formula that struck out ousia (“essence”) language altogether and confessed the Son simply “like the Father.” It was the high-water mark of Homoian imperial Christianity, and the moment Jerome immortalized in a single famous sentence: “ingemuit totus orbis et Arianum se esse miratus est” — “the whole world groaned and marvelled to find itself Arian” (Jerome, Dialogus contra Luciferianos 19 [PL 23:172]; trans. NPNF II/6). That sentence describes the West Ambrose was born into and the settlement he set out to undo. The Homoian creed was for a season not the doctrine of a faction but the official faith of the empire, enforced by exiles and depositions; and though the deaths of Constantius (361) and of the Arianizing Valens at Adrianople (378) loosened its grip, in the Latin Danubian provinces and at the court of Milan it survived as a living power into Ambrose’s episcopate.

De Fide (On the Faith)

Ambrose’s first great doctrinal work was written not for a synod but for an emperor. The young Western emperor Gratian, about to march east to aid his uncle Valens against the Goths, asked Ambrose for a statement of the faith — an “antidote against Oriental sophistry,” in the older phrase — and Ambrose responded with De Fide (Ambrose, De Fide, prologue; Catholic Encyclopedia, St. Ambrose; NPNF II/10 Prolegomena). The work grew in stages: Books I–II first, then Books III–V added somewhat later, making the five books we have (Ambrose, De Fide [CSEL 78, ed. Faller]; trans. NPNF II/10). [Disputed: Books I–II are dated by most scholars to late 378, soon after the catastrophe of Adrianople (9 August 378), and favored there by Daniel H. Williams; some place them in 380, after Gratian’s meeting with Ambrose at Milan; Books III–V are broadly agreed to belong to c. 380. The manuscript tradition preserves both a two-book and a five-book edition (Markschies, critical edition; Williams, Ambrose of Milan, 128–153).]

De Fide is a sustained Latin defense of the Nicene confession of the Son’s full and equal divinity. Ambrose marshals the Scriptures against the Arian proof-texts, insists on the Son’s eternity and consubstantiality with the Father, and exposes the subordinationist reading of passages such as John 14:28 (“the Father is greater than I”) by referring them to Christ’s humanity, not his divinity. He works through the standard Arian arsenal of texts — the Son’s being “begotten” (which the Arians read as “made” and “having a beginning,” and which Ambrose insists denotes an eternal, timeless generation from the Father’s own substance, not a creation in time), the passages of ignorance and subordination (the Son not knowing the day or the hour, Mark 13:32; “my Father is greater than I”; the prayer in Gethsemane), and the wisdom “created” of Proverbs 8:22 — and refers each either to the economy of the Incarnation, where the Son truly assumed the limitations of a real humanity, or to the eternal relation of origin within the one Godhead, in which the Son is “from” the Father yet in no way less than the Father. Against the Homoian homoios he sets the full Nicene homoousios: the Son is not merely “like” but one in essence, true God of true God, equal in eternity, power, and worship (Ambrose, De Fide 1.7–9, 2.8–11, 3.7; trans. NPNF II/10). The work is uneven — the work of a man teaching himself as he writes — and his Homoian opponents seized on its weaknesses. Palladius of Ratiaria later wrote a point-by-point rebuttal, mocking Ambrose’s logic and his philosophical roughness, charging him with self-contradiction and with not understanding the texts he cited (Palladius’s fragments, ed. Gryson, SC 267; Williams, Ambrose of Milan, 154–184). The criticism was not wholly unfair as logic; but the De Fide did what it was meant to do. It placed the full weight of the bishop of the imperial capital behind Nicaea, and it bound the emperor Gratian’s policy to the Nicene cause.

The Council of Aquileia (381)

The defeat of Western Arianism was sealed at a council Ambrose effectively ran. Gratian had at first intended a general council to settle the Western disputes — a Latin counterpart to the great council the East was holding at Constantinople. Ambrose persuaded him instead to convene a smaller, mainly North-Italian gathering of his own supporters, which met at Aquileia on 3 September 381 (Ambrose, Ep. extra coll. 4 [Maur. 10]; Liebeschuetz and Hill, TTH 43, 221–222; McLynn, Ambrose of Milan, 124–137). The aged bishop Valerian of Aquileia presided in form, but Ambrose dominated in fact, conducting the interrogation himself.

[Disputed: the number of bishops present is given as thirty-four in modern scholarship (Liebeschuetz and Hill) and as thirty-two in the older encyclopedia tradition; the discrepancy turns on counting conventions, but the substantive point is agreed — it was a small council of Ambrose’s own party, not the general council Palladius had wanted.] The two leading Illyrian Homoian bishops, Palladius of Ratiaria and Secundianus of Singidunum, came expecting a hearing among equals and found themselves on trial.

The procedure can be followed almost minute by minute, for an exceptional thing happened: a notary took down the proceedings verbatim, and the resulting acts, the Gesta Concilii Aquileiensis, survive — one of the very few stenographic council records preserved from the early Church (CSEL 82.3, ed. Zelzer; trans. in Liebeschuetz and Hill, TTH 43). They show Ambrose, not the nominal president, conducting the whole affair as a prosecutor conducts a cross-examination. He had prepared his ground: the council opened not with free debate but with the reading of a letter of the arch-heretic Arius, and Palladius was required to pronounce, clause by clause, whether he condemned or accepted its propositions. The trap was sprung on the question of the Son’s divinity. When the Arian letter was read out saying that the Son is “true God” only in a derived or titular sense, Ambrose pressed Palladius directly: “Is Christ true God?” — and Palladius, cornered, would not give the Nicene answer plainly, equivocating that the Son is God but evading the word “true” in the full sense, until his evasions stood exposed in the record (Gesta 13–43; Williams, Ambrose of Milan, 169–184). The John 14:28 text was the pivot the Homoians had always leaned on — “the Father is greater than I” — and Ambrose turned it against Palladius by forcing him to say whether the Son’s inferiority was according to the flesh (which all confessed) or according to the Godhead (which was the Arian claim); pinned to the latter, Palladius condemned himself out of his own mouth. Palladius repeatedly protested that he would not be judged by so partial a body, demanded the full council Gratian had promised, objected that lay imperial officials and a stacked bench of Ambrose’s allies could not try his faith, and finally fell largely silent, refusing to answer further — whereupon the assembled bishops pronounced sentence. Palladius and Secundianus, with the presbyter Attalus, were condemned and deposed for refusing to confess the Son’s true and equal divinity (Ambrose, Ep. extra coll. 4 [Maur. 10], §§8–9; Gesta Concilii Aquileiensis). Palladius’s protest was not baseless. He later wrote an apology against the council, charging that its rigged composition and its substitution of interrogation for genuine debate made it no true council; this survives in fragments as marginal scholia on a manuscript of the Gesta (ed. Gryson, SC 267) — the losing side’s voice, rare in this period and worth preserving precisely because the victors so rarely let it survive.

Aquileia and Constantinople

Aquileia was a regional Western synod, not an ecumenical council, and the distinction matters. In the same year, 381, the First Council of Constantinople — the Second Ecumenical Council — met in the East under Theodosius, reaffirmed Nicaea, completed the creed’s confession of the Holy Spirit against the Pneumatomachi, and gave the universal Church the symbol recited in the Liturgy ever since (see Orthodoxy Guide: The Ecumenical Councils). Its decisions had already been given the force of law by Theodosius (CTh 16.1.3, 31 July 381) just before Aquileia met. Ambrose’s follow-up letters from Aquileia attempted to reach into Eastern affairs — the Antiochene schism, the see of Constantinople — and were rebuffed; the lasting ecumenical authority belonged to Constantinople, while Aquileia did the regional work of breaking the Homoian episcopate of the Latin Danubian provinces (McLynn, Ambrose of Milan, 137–150).

Together, the two councils of 381 mark the turning of the tide: in the East by the act of an ecumenical council, in the West by Ambrose’s management of a provincial one and the imperial enforcement that followed. Western Arianism did not vanish instantly — the court’s Homoian party would mount its bid for a Milanese basilica only five years later (see The Altar of Victory and the Basilica Crisis).

But the most consequential survival of Homoian Christianity lay not within the empire at all but among the Germanic peoples beyond the frontier, and here Aquileia’s victory proved strangely partial. The Goths had been evangelized in the mid-fourth century by Ulfilas (Wulfila), consecrated by the Homoian bishops of the Constantian church and translator of the Bible into Gothic; the faith he carried was the “like the Father” creed of that imperial moment, and the Goths held to it with tribal tenacity long after the empire had abandoned it. As the Gothic, Vandal, Burgundian, and Lombard peoples settled within the dissolving Western empire, they brought their Homoian Christianity with them, so that across much of the former West an Arian ruling caste governed a Nicene Catholic population. The Vandals in Africa persecuted the Nicene clergy under Geiseric and Huneric; Ostrogothic Italy under Theodoric maintained a parallel Arian church in Ravenna (whose Arian baptistery still stands); the Visigoths in Spain did not abandon Homoianism until Reccared’s conversion at the Third Council of Toledo in 589; and the Lombards carried it into Italy as late as the seventh century. Homoian Christianity thus outlived its imperial defeat by some two and a half centuries on Germanic soil — a reminder, against any triumphalist reading, that what Ambrose and the councils of 381 secured was the allegiance of the imperial church, not the extinction of the doctrine. Yet within the institutions that mattered to the future of catholic Christendom, the public, official Latin church had been bound to Nicaea, and Ambrose, more than any other single man, had bound it.

[Disputed: Williams (Ambrose of Milan, 1995) cautions against the later, triumphalist narrative — found already in the fifth-century historians and in Paulinus — that reads the Nicene victory as swift and inevitable; he stresses how contested and gradual the outcome actually was, and how much it owed to imperial power and political management rather than to argument alone.]

References

Ambrose of Milan. De Fide (ad Gratianum), 5 books [CSEL 78, ed. Faller]; trans. NPNF II/10 (de Romestin); crit. ed. Markschies (Brepols/Herder, 2005). On the Nicene confession of the Son.
Ambrose of Milan. Epistula extra collectionem 4–6 [Maurist 10–12]; trans. NPNF II/10 and Liebeschuetz and Hill, TTH 43. The synodal letters of Aquileia.
Gesta Concilii Aquileiensis [CSEL 82.3, ed. Zelzer]. The verbatim acts of the council; trans. in Liebeschuetz and Hill, TTH 43.
Jerome. Dialogus contra Luciferianos 19 [PL 23:172]; trans. NPNF II/6. “The whole world groaned and marvelled to find itself Arian,” on Rimini 359.
Gryson, Roger, ed. Scolies ariennes sur le concile d’Aquilée. Sources Chrétiennes 267. Paris: Cerf, 1980. Palladius’s fragments and the later Arian scholia.
Williams, Daniel H. Ambrose of Milan and the End of the Nicene-Arian Conflicts. Oxford: Clarendon Press, 1995, esp. 128–184. On De Fide, Aquileia, and against the triumphalist narrative.
McLynn, Neil B. Ambrose of Milan: Church and Court in a Christian Capital. Berkeley: University of California Press, 1994, 124–150. On Aquileia and its limits.
Liebeschuetz, J. H. W. G., and Carole Hill. Ambrose of Milan: Political Letters and Speeches. TTH 43. Liverpool: Liverpool University Press, 2005, 121–230.
Dudden, F. Homes. The Life and Times of St. Ambrose. 2 vols. Oxford: Clarendon Press, 1935, 1:191–255.