I think condescending really is the wrong approach to people that have crazy beliefs like climate change deniers, holocaust deniers and anti-vaxxers. These are people that choose to believe in something dogmatic that is absolutely not covered by facts and no rational discussion will be able to convince them otherwise.

In my opinion, people should be less accepting of stupidity like this. There are opinions that should not be accepted so condescension is the wrong approach, rejection and ostracization are the ones that are right in my opinion.