But the Christianization of the inland Pontic districts began only about the middle of the 3rd century and was largely due to the missionary zeal of Gregory Thaumaturgus, bishop of Neocaesarea.
ST GREGORY (c. 213-c. 270), surnamed in later ecclesiastical tradition Thaumaturgus (the miracle-worker), was born of noble and wealthy pagan parents at Neocaesarea in Pontus, about A.D.
The principal works of Gregory Thaumaturgus are the Panegyricus in Origenem (Eis 't ptybniv iravrnvpucos Xbyos), which he wrote when on the point of leaving the school of that great master (it contains a valuable minute description of Origen's mode of instruction), a Metaphrasis in Ecclesiasten, characterized by Jerome as " short but useful "; and an Epistola canonica, which treats of the discipline to be undergone by those Christians who under pressure of persecution had relapsed into paganism, but desired to be restored to the privileges of the Church.
An earlier origin has been claimed for it on the ground that it is mentioned in sermons of Athanasius and of Gregory Thaumaturgus, but both of these documents are now admitted to be spurious.
As thus defined, the collection contains the following documents: firstly, the eighty-five Apostolic Canons, the Constitutions having been put aside as having suffered heretical alterations; secondly, the canons of the councils of Nicaea, Ancyra, Neocaesarea, Gangra, Antioch, Laodicea, Constantinople (381), Ephesus (the disciplinary canons of this council deal with the reception of the Nestorians, and were not communicated to the West), Chalcedon, Sardica, Carthage (that of 4 19, according to Dionysius), Constantinople (394); thirdly, the series of canonical letters of the following great bishops - Dionysius of Alexandria, Peter of Alexandria (the Martyr), Gregory Thaumaturgus, Athanasius, Basil, Gregory of Nyssa, Gregory of Nazianzus, Amphilochus of Iconium, Timotheus of Alexandria, Theophilus of Alexandria, Cyril of Alexandria, Gennadius of Constantinople; the canon of Cyprian of Carthage (the Martyr) is also mentioned, but with the note that it is only valid for Africa.