Prior to the onset of the Reformation in the early 16th century, there were no non-Catholics in Europe. The nations states of Europe were Catholic, and most all people were Catholic
One theme that has been the source of a lot of anti-Jewish persecution over the centuries has been that of the Jews as Christ Killers. During the early years of the Church, the Christians were mostly Jewish converts, and were a minority under the Jewish peoples, and they were badly persecuted by these Jews. The story of Paul’s conversion speaks of this, as he was one Jew who was on the hunt, and was present at the stoning of the first martyr, Stephen, by the Jews.
After the destruction of Jerusalem in around 70 a.d. and the diaspora of Jews across the Roman Empire, which later became the nations of Europe, the Jews found themselves a minority, and at the mercy of the Christians. I don’t think there is any question that Jews over many centuries in Europe suffered horribly at the hands of Christians. Still, it isn’t exactly correct to say that these things are “unbiblical.” The New Testament tells many stories of Jews persecuting Christians. My guess is that Christians in Europe figured that turnabout is fairplay. And there is absolutely no question that the Gospels depict the Romans as hesitant to crucify Jesus, but pressured into doing so by the Jewish religious leaders. These things, coupled with the natural “oddness” of the Jews in Europe, who refused to intermarry, or have much to do with the non-Jewish neighbors, except in doing business with them, helped create an atmosphere of occasional persecution. It isn’t accurate to say that Jews were relentlessly or universally persecuted. But persecutions arose here and there and were often caused by complex sets of circumstances, rather than being the sole result of statements by popes or bishops.
So, what we have is an anti-semitism with multiple causes. Maybe popes could have done more to rein it in, and didn’t. Maybe they didn’t have the power to do so. After all, mobs usually aren’t easily controlled. But Protestants were just as bad, and they didn’t have a pope to obey.
Let me put it this way: You have a hard time believing that corrupt popes didn’t corrupt doctrine and dogma. I have a hard time believing that most leaders of the Church, both Protestant and Catholic, didn’t do their best to keep the anti-semitism under some control. You know, there weren’t that many Jews, and still aren’t. If there hadn’t been some restraint, it wouldn’t have been all that hard to wipe them out completely.
But I just have to pipe up in this discussion.