I don't agree

We all have our own unique ideas and opinions. My thirty-two year old brother and I still to this day can fight like cats and dogs, over things as banal as the origins of the Selkie legends; one would think that at more than nine years my senior he'd concede and let me be right once in a while. Especially when I was actually correct about the origins of the Selkies. I respect that we all have a different opinions, most of the time I can even empathize with other individuals ideas. We all come from different socioeconomic backgrounds, have had different experiences and exposures that have shaped our worlds views. But I can guarantee that what you think is funny banter or a shared opinion with the girl behind the espresso counter isn't as funny or a mutually accepted as you think. I'm smiling not because its funny or because I agree. I'm smiling because its the nicest way I can think of to get you to leave and honestly I don't know how to respond. Even now nine hours after I had to deal with a bizarre customer I still don't know what I could have, or even what I should have said or done.

What do I say to an elderly man from the mid-west, visiting family for the Thanksgiving holiday, who starts shit talking the "Mexican aliens?" How do I tell him that even though I'm of Indo-European decent, I am unbelievably offended by his saying that legal immigrants are just as bad as illegal? How do I tell him that I don't agree? How do I say that the problem doesn't lie with illegal immigrants but with indiscriminate employers and dishonest people cutting corners on Labor and Industries by paying cash wages? How do I tell him that the jobs they are "stealing" are the jobs that his unemployed grandson thinks are below him?  I could give a moving and exceptionally thorough lecture on human rights and social justice, but in the five minutes between when he walks in the door and when he walks out with his coffee, will anything I say really make a difference? How do I tell a close-minded individual that their ignorance offends and  then still smile and tell them to come back again now real soon.