Hypsistarians, "i.e. worshippers of the Hypsistos (Greek: Ὕψιστος, the "Most High" God), is a term appearing in documents dated about 200 BC to about AD 400, referring to various groups mostly in Asia Minor (Cappadocia, Bithynia and Pontus), and on the South Russian coasts of what is today known as the Black Sea.16 Once when we were going to the place of prayer, we were met by a female slave who had a spirit by which she predicted the future. She earned a great deal of money for her owners by fortune-telling. 17 She followed Paul and the rest of us, shouting, “These men are servants of the Most High God, who are telling you the way to be saved.” 18 She kept this up for many days. Finally Paul became so annoyed that he turned around and said to the spirit, “In the name of Jesus Christ I command you to come out of her!” At that moment the spirit left her.
"Some modern scholars identify the group, or groups, with God fearers, that is uncircumcised semi-proselytes to, & sympathizers with, Hellenistic Judaism[1][2]
"In the Septuagint the word "hypsisto-" occurs more than fifty times as a title for Yahweh (the Tetragrammaton) or in direct relation to him (most often in the Psalms, Daniel, and Sirach; Strong's #5310) ...
"Contemporary Hellenistic use of ὕψιστος (hýpsistos) as a religious term appears to be derived from and compatible with ... the Septuagint. (Greek ύψίστος translating Hebrew elyon עליון English "highest".)
"Persius (34-62) may have had Hypsistarians in view when he ridiculed such hybrid religionists in Satire v, 179–84; and Tertullian (c.160 – c.225 AD) seems to refer to them in Ad nationes, I, xiii ...
"The names Hypsianistai, Hypsianoi first occur in Gregory of Nazianzus (Orat., xviii, 5) [his father belonged in his youth] and the name Hypsistianoi in Gregory of Nyssa (Contra Eunom., II), ie. about AD 374, but a great number of votive tablets, inscriptions and oracles of Didymos and Klaros establish beyond doubt that the cult of the Hypsistos (Hypsistos, with the addition of Theos 'god' or Zeus or Attis, but frequently without addition) as the sole God was widespread in the countries adjacent to the Bosphorus ...
"Hypsistarians are probably referred to under the name 'Coelicoloe' in a decree of the Emperors Honorius and Theodosius II (AD 408), in which their places of worship are transferred to the Catholics."