I disagree... there are perfectly valid reasons to develop anti-semitism because of generalisation from your experience. In this instance the person has generalised about a group from valid experience with a few people. That doesn't make it morally right - and it's a position you can be talked down from if you're given the space and time to unpack it. Nothing about calling someone evil for holding said views means they're inherently evil. If they cannot be rationalised with, they refuse to acknowledge reality in a meaningful way and continue to persecute others even when they know such a thing is morally wrong, that's when we can start throwing the 'evil' word around.