IPSISTARIANI (Hypsistariani).—A sect of the fourth century widespread in Cappadocia, whose existence even in the ninth century is recalled by Nicephorus, patriarch of Constantinople (Antirrhet. adversus Constantinum Copronymum, 1, 5).
The name derives from the fact that the adherents of the sect claimed to believe in one God alone, the Most High (τὸν ὕψιστον), perhaps in protest against the Trinitarian faith of Nicaea; hence the name ὑψιστάριοι. Their
doctrine was a mixture of Hellenic paganism and Judaism. From the former they adopted certain idolatrous practices, such as the worship of fire and light, though without sacrifices or idols; from Judaism, certain legal observances, such as the sanctification of the Sabbath, and certain precepts concerning food, as well as the distinction between pure and impure, while they rejected circumcision.
The Ipsistianoi, of whom St. Gregory of Nyssa speaks (contra Eunomium, 2: PG 45, 482 ff.), seem to have been identical with them. They too acknowledged one God alone, whom they called the Most High or Pantocrator, but not Father. The i. in some way recall the Messalians or Euphemites described by Epiphanius (Haer., 80), the Rheosebei whom St. Cyril of Alexandria mentions (De adoratione in spir. et veritate, 3: PG 68, 282), and the Caelicoli of Africa, of whom St. Augustine speaks (Ep., 44, chap. 6, no. 13: PL 33, 180).
Since the information is scant, historians of religion do not agree in their opinions concerning the i. Thus, while Ullman considers them an eclectic sect combining elements of Judaism and Hellenism, Böhmer instead judges them to be a remnant of Sabaism.