An Arian sect originating in the fourth century
Acacians, the, known also as the HOMOEANS, an Arian sect which first emerged into distinctness as an ecclesiastical party some time before the convocation of the joint Synods of Ariminum (Rimini) and Seleucia in 359. The sect owed its name as well as its political importance to Acacius, Bishop of Caesarea, οἱ περὶ ᾿ Ακάκιον, whose theory of adherence to scriptural phraseology it adopted and endeavored to summarize in its various catch words: ὅμοιος, ὅμοιος κατὰ πάντα, κ. τ. λ.
In order to understand the theological significance of Acacianism as a critical episode, if only an episode, in the logical, as well as in the historical progress of Arianism, it is needful to recall that the great definition of the Homoousion, promulgated at Nicaea in 325, so far from putting an end to further discussion, became rather the occasion for keener debate and for still more distressing confusion of statement in the formulation of theories on the relationship of Our Lord to His Father, in so far as that relationship constituted a distinct tenet of orthodox belief. Events had already begun to ripen towards a fresh crisis shortly after the advent of Constantius to sole power, on the death of his brother Constans in the year 350. The new Augustus was a man of vacillating character with an unfortunate susceptibility to flattery and a turn for theological debate (Ammianus, XXI, xvi) that soon made him a mere puppet in the hands of the Eusebian faction. Roughly speaking there were at this period but three parties in the Church: the Orthodox or Nicaean party, who sympathized for the most part with Athanasius and his supporters and who insisted on making his cause their own; the Eusebian or Court party and their bewildered Semi-Arian followers; and, last of all, and not least logical in their demands, the Anomoean party which owed its origin to Aetius. In the summer of 357, Ursacius and Valens, the astute, but not always consistent advocates of this latter group of dissidents in the West, through the influence which they were enabled to bring to bear upon the Emperor by means of his second wife, Aurelia Eusebia (Panegyr. Jut. Orat., iii; Ammianus, XX, vi, 4), succeeded in bringing about a conference of bishops at Sirmium.
In the Latin creed put forth at this meeting there was inserted a statement of views drawn up by Potamius of Lisbon and the venerable Hosius of Cordova, which, under the name of the Sirmian Manifesto, as it afterwards came to be known, roused the whole of the 'Western Church and threw the temporizers of the East into disorder. In this statement the assembled prelates, while declaring their confession in "One God, the Father Almighty, and in His only-begotten Son, Our Lord Jesus Christ, generated from Him before the ages," recommended the disuse of the terms ousia (essence or substance), omooision (identical in essence, or substance), and omoiousion (similar in essence, or substance), "by which the minds of many are perturbed"; and they held that there "ought to be no mention of any of them at all, nor any exposition of them in the Church, and for this reason and for this consideration that there is nothing written about them in divine Scripture and that they are above men's knowledge and above men's understanding" (Athan., De Syn., xxviii; Soz., ii, xxx; Hil., De Syn., xi). The effect of these propositions upon conservative opinion was like that of the proverbial spark in a barrel of gunpowder. As we look back from the standpoint of modern Catholicism upon the circumstances of this publication, it is impossible not to see that they occasioned the crisis upon which the whole subsequent history of Arianism turned. In spite of the scriptural disclaimer against the employment of inscrutable terms, nearly all parties instinctively perceived that the Manifesto was nothing else but a subtly Anomoean document.
The situation was assuredly rich in possibilities. Men began to group themselves along new lines, In the East, the Anomoeans turned almost as a matter of course to Acacius of Caesarea, whose influence was growing stronger at court and who was felt to be a shrewd and not too scrupulous temporizer. In the West, bishops like Ursacius and Valens began to carryon a like policy; and everywhere it was felt that the time called once more for concerted action on the part of the Church. This was precisely what the party in favor with the Emperor Constantius were eager to bring about; but not in the way in which the Nicaeans and Moderates expected. A single council might not be easily controlled; but two separate synods, sitting, one in the East and the other in the West, could be kept better in hand. After a number of preliminary conferences accompanying an inevitable campaign of pamphleteering in which Hilary of Poi tiers took part, the bishops of the Western portion of the Empire met at Ariminum towards the end of May, and those of the East at Seleucia in the month of September, 359. The theological complexion of both Synods was identical, at least in this, that the party of compromise, represented at Seleucia by Acacius and at Ariminum by Ursacius and Valens, was politically, though not numerically, in the ascendant and could exercise a subtle influence which depended almost as much on the argumentative ability of their leaders as on their curial prestige. In both councils, as the result of dishonest intrigue and an unscrupulous use of intimidation, the Homoean formula associated with the name of Acacius ultimately prevailed. The Homoousion, for which so much had been endured by saintly champions of orthodoxy for over half a century was given up and the Son was declared to be merely similar to—no longer identical in essence with—the Father. St. Jerome's characterization of the issue still affords the best commentary, not only on what had come to pass, but on the means employed to obtain it. The whole world groaned in wonderment to find itself Arian—ingemuit totus orbis et Arianum se esse miratus est. It was Acacius and his followers who had skillfully managed the whole proceeding from the outset. By coming forward as advocates of temporizing methods they had inspired the Eusebian or Semi-Arian party with the idea of throwing over Aetius and his Anomoeans. They thus found themselves thrust into a position of importance to which neither their numbers nor their theological acumen entitled them. As they had proved themselves in practice all through the course of the unlooked-for movement that brought them to the front, so were they now, in theory, the exponents of the Via Media of their day. They separated themselves from the orthodox by the rejection of the word omooousios; from the Semi-Arians by their surrender of the omoiousios; and from the Aetians by their insistence upon the term omoios. They retained their influence as a distinct party just so long as their spokesman and leader Acacius enjoyed the favor of Constantius. Under Julian the Apostate, Aetius, who had been exiled as the result of the proceedings at Seleucia, was allowed to regain his influence. The Acacians seized the occasion to make common cause with his ideas, but the alliance was only political; they threw him over once more at the Synod of Antioch held under Jovian in 363. In 365 the Semi-Arian Synod of Lampsacus condemned Acacius. He was deposed from his see; and with that event the history of the party to which he had given his name practically came to an end.