I am vegetarian and my wife is not. If we eat out, the waiter always assumes that my wife is the vegetarian and they have a confused look on their face when I tell them that the vegetarian dish is for me not her. They don't bother to ask me they just give me the dish with the meat in it. That is ignorance.
I went for a job interview once and on the application form it asked me for my hobbies, why I don't know but I wrote, writing blogs and drawing pictures with pens
Well, when I got to the interview the man asked me what my real hobbies are. I said they are my hobbies. I love to write entries in my blog and draw detailed pictures with just ink pens. The manager went red in the face and said don't lie to me. You don't need to impress me. I said that is my two main hobbies.
A black man that I knew told me he hates rap music and someone asked him what rap music he likes, he said that rap music is not music to him it is noise. The person asking would not accept that he hates rap music. He said you're black all black people love rap music. The man replied, I don't and I am black.
Anyway when a person is persistently ignorant about something then the best thing is to give short answers and ignor them. Yes or no. That is it, don't waste your vocal cords on people that embrace ignorance.