Resolutely refusing to accept a conventional understanding is a statement of certainty.
That’s different from honest skepticism. The skeptic offers an open mind and is clear about what would be necessary to earn enthusiastic support.
The denialist, on the other hand, is sure. Now and forever. This certainty probably doesn’t come from the matter being discussed. Instead, it’s based on external factors, a story, a cultural connection, something that is fueled by the feeling that comes from refusing to examine the issue, not by honest inquiry.
Skepticism is gutsy, denialism is based on fear.