St. Paul's Epistles to the Colossians and Philemon A...

Hefele (Conciliengeschichte I. p. 71) places the date of this council before A.D. 150. But if the testimony of Eusebius is worth anything, this is impossible; for he states that the writings of Claudius Apollinaris against the Montanists were later than his Apology to M. Aurelius (see p. 59, note 183), and this Apology was not written till after A.D. 174 (see p. 61, note 187). The chronology of Montanism is very perplexing, but Hefele’s dates appear to be much too early. The Chronicon of Eusebius gives the rise of Montanism under A.D. 172 or 173, and this statement is consistent with the notices in his History. But if this date be correct, it most probably refers to Montanism as a distinct system; and the fires had probably been smouldering within the Church for some time before they broke out.

It will be observed that the writer of the Synodicon identifies Theodotus the Montanist (see Euseb. H.E. v. 3) with Theodotus the leather-seller who was a Monarchian. There is no authority for this identification in Eusebius.