ACACIO, bishop of CESAREA. — A disciple and then, from 340, successor of Eusebius the historian in the see of Caesarea in Palestine. In the Arian controversy he was not in favor of Nicene orthodoxy, but neither did he explicitly and consistently take sides in favor of Arius. At a council held at Constantinople (360) and presided over by him, he succeeded, protected by the emperor Constantius II, in having the formula of faith of the Council of Rimini adopted, in which the Son of God was proclaimed similar to the Father, while the use of the terms usia and hypostasis was forbidden. At the Council of Antioch (363) he drew closer to the Nicene faith by admitting that the Son was similar in substance to the Father (ὕρωτος κατὰ ὠνῶν); cf. Epistola synodalis, in Mansi, III, 372), opportunistically deferential to the orthodoxy of the emperor Jovian; but he soon returned to his original position under his successor Valens. He died around 366.
The Acacians were named after him: those who, in the Arian controversy, refused to admit both the consubstantiality of the Son with the Father, defined at Nicaea, and the substantial likeness upheld by the semi-Arians, as well as the unlikeness affirmed by the Anomoeans, limiting themselves to asserting that the Son was similar to the Father, convinced that by doing so they remained faithful to the language of Sacred Scripture. They were therefore called Homoeans (from the Greek ὕρωτος). St. Jerome (De Viris illustr., 98) and Socrates (Hist. eccl., II, 4) mention some of the numerous writings of A., including a biography of his teacher and predecessor Eusebius, several commentaries on Ecclesiastes, and some “Various Questions” (Συμμετὰ ζητήματα).