> How do you stop both hate speech and censorship?

You don't. You instead crank up the censorship and -- more importantly -- the social stigma against bigotry. Change does not happen naturally and people don't get better, but if they get enough backlash from family and friends, people will eventually pretend to accept whatever it is you're trying to promote by censorship. This pretense will turn into genuine acceptance in future generations because they will grow up with not being able to be bigoted without clear and univocal backlash.