Answer:
Explanation:
This is actually in the wrong place. It should probably be in English or History, but I'll answer it anyway.
You need to start by seeing the way they were portrayed in cartoons, in writing (mainly newspapers), on the radio, in speeches and on the streets. Start with the Bible. The Old Testament was about the law mostly and behavior as much as anything. The people who lived and were governed by the OT generally were very pious unless they were rebellious sinners.
The New Testament is a slightly different matter. In most of Europe the peasantry thought the Jews were Christ Killers. That thought was dominent throughout the Middle Ages. It isn't true. Jesus was a Jew, so were the disciples, so were the huge crowds that followed Him to at least hear what he had to say.
It was only the ruling classes (The Pharisees, the Sadducees, and the scribes and teachers), that were not fond of Jesus. But that fact was not emphasized. Out of that picture and the displacement of the Jews after the Temple was destroyed, grew the caricatures of what the Jews were.
Anti Semitism was quite common in Europe. Most people fell for the propaganda that said the Jews were the spawn of the Devil. It became easy to kill those that were felt to be evil.
I urge you to start your own study of what happened. Start with the Inquisition.