Lol so young and nieve- "how do we fix this?" Pro tip: you can't.

Let me explain: that viewpoint that they have is a belief they would have and probably got it from their parents/culture so I'm guessing of about 40 years.

You can't change a belief that has been ingrained for that long overnight it would equally take a lifetime for them to change it's like going to a devoted Christian of 40 years and saying "Jesus isn't real"

Wake up will you.

Like what others have said prepare to move out and start your life together if you try convince them it will just get worse - challenging people's beliefs is not fun - respect it and move on