Doxx them.

What, that isn't allowed? Well neither is white supremacist hate speech. Fuck that trash.

Block em

Block users and instances is the only way.

Block user/community/instance.

Report if advocating for violence.

There's really isn't enough time to argue with everyone, and these people are probably used to being argued with, and might even take it as evidence of some big conspiracy. -- If you want to make changes in the word, there are more productive ways then arguing on obscure forums.

My answer is that it depends on several factors. The first and least impactful thing you can do (and that's in terms of both you and the other person) is to just block them. Next step up is that if they're not on a big instance that you get content from regularly, just block their instance. After that, report them to your instance owner - they might get blocked from interacting with your instance. And the more heavy-duty action is to reach out to their instance owner with evidence and make your concerns known - then if they get booted, you can continue as you were; and if they don't, block the instance.

Memes.

Fight fire with fire. Assume their gender. 🙂

I tag them as 'shit-head' and don't engage with them.