A bad hermeneutic & widespread disregard for the message of the Old Testament prophets leads to an incomplete gospel of what the kingdom of God really is.

Add to that the idea that the "church" somehow replaces Israel (because of unbelief) and you have fertile ground for antisemitism.

"In that day I will raise up the booth of David that is fallen
     and repair its breaches, and raise up its ruins
     and rebuild it as in the days of old."

Amos 9:11