Its a very simple formula that can be applied to many things, not just motivating hatred.
All it takes is someone to come up with an story and start spreading it. At fist they might not even be very successful but they go on and the more they tell the story the more the idea takes roots and becomes plausible. Some people might not believe it yet, but others start to. Then the person manages to convince a few people that are well respected in the community, so called figures of authority (doctors, teachers, business owners, etc). Once those respected people believe the story and start defending it, it's no longer just a story someone made up, it becomes widely accepted and many will think of it as a fact. After all, if Mr. This and Dr. That say it's true, it must be true.
Most people won't bother checking if the story is actually true and those who do will find themselves being mocked and cast aside. How dare they doubt what the figures of authority say? Some will be fearful and in order to avoid conflict they'll just keep to themselves, even if they know that the story has been a lie from the beginning.
However, there will always be a few that wont be afraid to do their research, get the facts together and tell the truth.
