Gregory Nazianzus in Cappadocia studied at Athens, and wrote in the middle and later part of the fourth century AD.
Orationes IV Adv. Julianum
The mutilations of the Phrygians distraught with the sound of the flute, and the tortures in the temple of Mithra, and the mystic cauteries, and the sacrifice of strangers amogn the Taurians.
In Sancta Lumina
Neither the divination of the Magi, nor inspection of the victims, nor the astronomy an horoscopy of the Chaldeans... nor Thracian orgies... nor the mystic rites of Orpheus... nor the painful endurance required of the initiates of Mithras, nor the mutilations of Osiris... nor the misfortunes of Isis, etc.
VII. 265 ff.
The mountain-haunting Bacchants in the train of Semele's son [Dionysus], and the ill-omened apparitions of nightly Hecate, and the shameful deeds and unrivalled orgies of the Mithraen shrine.