The Parthian example shows that religion and politics make a witch’s brew. Paul Johnson proposes in his History of the Jews, that the number of Jews who became Christians was probably larger than we are inclined to think. The break between Church and Synagogue occurred in the 2nd century and was as much a break in Judaism as anything. Nothing more bitter than a family quarrel, or in the political realm, a civil war, because the parties have so much in common, their differences so small but critical, like a cracked vase.
The question on the table is: who were the victims and who the aggressors.
I'm saying that's not even debatable -- after the second century Jewish Revolts against Rome, there are no serious examples of Jewish persecutions of Christians within the Empire.
And to judge by the vagueness of your Parthia example, very few outside it either.
The aggressors were Christians, whose populations doubled every century, and whose leadership exercised its political powers to suppress anyone and everyone -- be they heretics, pagans or Jews -- who didn't tow their line.
The irony, of course, is that unlike heretics and pagans, Jews were not targeted for extinction, thanks to St. Augustine of Hippo.
Instead, Jews were to be kept in a permanent state of subjection, so that they could serve as examples and warnings to Christians.
So after the second century Revolts, Jews were invariably the victims, and after 380 AD, Christians the aggressors.