Evolutionary biology describes a science. Darwinism doesn't.
The latter is a broader word which, until the wingnut community high-jacked it and converted it into a pejorative to advance their ridiculous beliefs, actually had a meaning.
So, the answer is to just stop using the word Darwinism, and reject any discussion during which it arises as a focus of an argument. If the wingnuts want to oppose science, force them to discuss science - not dogma.
In a nutshell, the job is to make it impossible for the wingnuts to keep using that word -- every time they do, they should get smacked upside the head and told what the correct terminology is or the conversation is over. Because, if you think about it, it's not really that unfair a demand, but I'm guessing it will drive the wingnuts to absolute distraction.Yup! That would be worth the effort.