You have heard of the expression "willfully ignorant"? That is racists. They do not think there is anything wrong with their opinion and quite frankly, do not wish to be convinced otherwise. They will also in some instances go to impossible lengths to OK their stance.
Singing Kumbaya will not bring people together, nor education, so what is left? Minimising the effect of racists on others and not giving it "oxygen".
I have some racist friends. Whenever they start getting racist, I shut them down. That is not where my commonality with them lays and I will not hear them talking that kind of shit around me. Opinions are like arseholes, everyone has one. They can think whatever hateful shit they like but I will not hear it or support it.