The important issue to focus on isn't that long ago people had a model that was not a good model of reality. The issue is that now we have better models and the person who claims they have an educated opinion should know it. Blindly holding to a model that has been shown to be inferior is what makes it an extremist belief.

The geocentric model was thought to be true for literally thousands of years by every astronomer and scientist. Today if someone claimed the geocentric model was true, we would consider it an extremist belief - even though pretty much every major astronomer believed it for thousands of years.