You can't build a functioning society that embraces people who reject the humanity of its other members. Or rather, you can build a society that way, but the moment that opinion is accepted you are on the road to terrible persecution of that out-group, whoever they are.
A pluralistic society can handle many different viewpoints, but it cannot give them equal value or acceptance.
Of course you can't, however many people have different definitions of "rejecting humanity" and you don't get to just define that however you want and then make anyone who doesn't agree with your definition the de facto outgroup.
A pluralistic society can handle many different viewpoints, but it cannot give them equal value or acceptance.