I recently bought Blood Passover written by Ariel Toaff. It's about how Jews used to kidnap Christian children and use their blood in religious rites. So far it's a good read.
Did it change your opinion on how you view the Jewish people?
Yes, I now see them as a menace to society
It is good that you are trying to learn new things about people but you should be more careful about the books you read. They might give you some misinformation and then you will make bad assumptions about people.
Have you read the book?
I think you should try not to judge all people of a religion just because some of them did a bad thing.