You shouldn't judge the entire group of people
John comes home from work upset that Mr. Goldstein overcharged him for his car service at the shop.
John wants to vent his anger.
John tells his family that he's upset how much the bill was and will probably go elsewhere next time.
John tells his family in a raised voice that all Jews are like that.
John's family consoles John and develops normally without any racist views.
John's family respects John less and possibly develop anti-semitic views themselves.