A large part of the old Testament is about the Jewish people and how they are God's chosen people. In the new testament Jesus made it (to the Christian perspective) so everyone gets to be in that chosen club. The crucifix is a roman thing even though the angy mob was Jewish, Jesus was also Jewish, many followers of Jesus were Jews etc. Also some prophecies in the book of revelations (last book in the bible) but I don't remember much off hand.

Add in the horrors of the Holocaust and its hard for people with a simplistic good or bad/binary worldview to even understand other perspectives.

You're mostly right and the Christian church has been deeply antisemitic for most of its history.

The Holocaust had a deeply chilling effect on those aspects of the Christian church and while the overt antisemitism has largely vanished the last 80 years, the theology of most Christians still has antisemitic thought baked in to it.