Yantan, Massuh states something very good and very applicable. At your age, it is very good for you to follow his instructions to the "T". The reason I say this is your situation is very near exactly the situation I had with my wrestling partner who didn't know I was Jewish. After a few drinks we were walking to my "rookie" party, as he was 2 years older than I, and he made an antisemitic comment. In the middle of the road, I asked him a few direct questions. He was the product of our "enlightened" and "Progressive" educational system here of which his professor was dismissed from services, which of course was the fault of the Jews because we "run the world"...
In any event, I asked him "What would you do if your best friend was Jewish?" after not 10 minutes prior he said the best friends line.... He said to me "I wouldn't be friends with a Jew.", and then "I'd break his legs". I then said to him "I'm a Jew" and I challenged him flat out in that I'd love to see him "try" to break my legs. Of course he backed down and said "you're a Jew?" "You don't have horns" or some such rubbish.
After I confronted him, he spent the next year asking questions and telling me what he "learned" while under this Malcom Ross [censored]. In the end, he is now a very Zionistic, Pro-Israel, Jew supporting Christian who beats up Nazi's and confronts "white supremacists" with his, now learned friends, whenever he happens to be in the situation. So people do change but they must be confronted and sometimes with force.
What Massuh says is spot on. Walk up to him and smack him as hard as you can.... The walk away... and do exactly what Massuh says. Memorize his wise words.... People like this MUST be confronted....