Many people seem to assume that those who disagree with them on something basic must be stupid.
I understand the frustration of fundamental disagreement. I used to fall into this trap, too.
Then, I got a fair amount of exposure to a group of very diverse high IQ people. My most striking experience was that they are as likely to agree with you, as to have a completely opposite mindset, arguing things you would never consider reasonable.
It is appealing to equate a person's disagreement with one's basic values with stupidity, but this is usually not the case.
I like to compare IQ to the horse power of a car engine. A stronger engine means you can reach your destination faster, but it doesn't dictate where you're going to go.
You're more likely to find yourself in the same destination - having similar opinions - with a bunch of people with large IQ variations. It is appealing to characterize a person as smart because they agree with you, but again, this is not necessarily the case.