Last time we saw that Athanasius’ fluency in the Word was, in Gregory’s view, his chief characteristic. The importance of the Word for the Arian conflict returns again later in the oration.
The Council of Nicaea spoke against, but did not end, the Arian problem, and so Athanasius saw much conflict in its wake. Speaking of the Council of Seleucia (359), Gregory says:
The ancient and pious doctrine which defended the Trinity was abolished, by setting up a palisade and battering down the Consubstantial: opening the door to impiety by means of what is written, using as their pretext, their reverence for Scripture and for the use of approved terms, but really introducing unscriptural Arianism. (Oration 21.22)
The Arians used Scripture to make their case, of course; but they used it badly, as a pretext. Notice what Gregory does not do here: he does not say that, because the heretics used Scripture just as the orthodox did, the orthodox had to find some tertium quid for adjudicating the case.
They did use a term not found in Scripture, it is true–the “consubstantial” or homoousion on which the entire Christological controversy hinged. This may have made the orthodox appear revolutionary in contrast to the Arians’ use of “approved terms.” But the homoousion was used precisely to combat what Gregory calls “unscriptural Arianism.”
There is the key: the problem with Arianism was that, in spite of its use of Scripture as pretext and its use of traditional terminology in a way that prescinded from what an orthodox doctrine of God required, it actually undermined the teaching of Scripture. While appearing traditional, Arianism’s traditionalism cloaked revolution–a revolution against the Scriptures. This fact, in turn, explains why the battle over Arianism was fought primarily on the grounds of exegesis and reason–a battle to safeguard what was, for Gregory, the real “ancient and pious doctrine” over against the pirated pseudo-pious off-brand substitute peddled by the Arians.