TD - "I would argue that racial Antisemitism has its roots in the religious Anti-Judaism..."
Agreed.
One of the things that I was very surprised to learn recently was that historic Judaism didn't necessarily view Genesis as factual, literal history.
More and more dominant elements of Christianity did, however (for cosmetological reasons), and I suspect that its leaders - knowing this - began to cast Jews (and by extension, Judaism) in a negative light to keep their subjects from learning this.
After all, if they associated with Jews, learned a bit of their traditions and theology, and subsequently realized that the actual Old Testament authors themselves didn't view their writings as infallible or "set in stone", it couldn't help but undermine the Church's authority in their eyes.
I could be wrong.