That opinion itself is quite a shockingly revisionist statement, to simply wave a broad brush like that at a rather complex time period and then apply modern political coloring to ancient history.
I see no attempt at nuance here, so taking this at face value, are we then to simply dismiss Pliny the Younger's writings to Trajan about persecution? Should we ignore Hadrian's note of slanderous attacks on Christians? Was Tacitus writing also 'myth' in saying that Nero blamed Christians for the fire in Rome?
...To get rid of the report, Nero fastened the guilt and inflicted the most exquisite tortures on a class hated for their abominations, called Chrestians by the populace. Christus, from whom the name had its origin, suffered the extreme penalty during the reign of Tiberius at the hands of one of our procurators, Pontius Pilatus, and a most mischievous superstition, thus checked for the moment, again broke out not only in Judæa, the first source of the evil, but even in Rome, where all things hideous and shameful from every part of the world find their centre and become popular.
— Tacitus' Annals 15.44
https://en.wikipedia.org/wiki/Persecution_of_Christians_in_t...
This was a complex period in history, I would be wary of anyone making sweeping judgements or applying modern political coloring which acts to cloud issues rather than to illuminate history.