After looking at it again, it looks like that is how the other website deals with links in their forum. Even so, can it hurt my site since it is a white supremacist site?

that is how the other website deals with links in their forum

Clarify, please. Are there two unrelated sites-- the ugly one and the forum-- or is it the ugly site's own forum? Is it one of those "Leaving Facebook" type setups where their internal link points to their own site, and then there's a second link taking users to the real target?

Since they're coming from a forum, do the unwanted requests always have the same referer? (Hostname, that is, not necessasrily the specific page.) Are you purely concerned with the search-engine aspect, or would you also like to prevent unattractive humans-- that is, the real-life forum visitors-- from seeing your site at all?

If the site doing the redirecting is a "real website" one possible solution is:

Move the content from the current page to a new URL -- No redirect.
Update all internal links and external links (if possible) to the new URL of the content.
Replace the content of the page you moved with a page of content about equality.
If necessary, be an "innocent visitor" who sends an email and wants to know why the site doing the redirecting sends people to a site about equality from the forum.

Wait for the redirects to be removed and/or pointed somewhere else.

Well done TMS.

There are a ton of nuances as you well know, but I'd do something very similar except for the "innocent visitor" email. It's a secondary step that has a lot of associated overhead.

Whenever possible, I like to minimize impact and exposure.

Sincerely, people need to start stepping up and doing what you just did.
That is the point of the forum after all.

Move the content from the current page to a new URL -- No redirect.
Update all internal links and external links (if possible) to the new URL of the content.
Replace the content of the page you moved with a page of content about equality.

Yes, this will solve the problem.

The question now is: does the page will regain its ranking in Google? And if so, how soon?

To OP... do you have any reason to believe that this was done with the deliberate intention to harm your site?

Thanks for the replies. I got a reply on the Google Webmaster forum that it shouldn't hurt my site because it is a nofollowed link, which I didn't realize.

I'd still move the content of the page and switch it to a page about equality based on general principal, because I don't play the "skin color" or "nationality" games, in fact, I think they're complete BS, especially when people think about it a bit -- I mean, yeah, it's fun to compete and "talk some ish" about who's better than who, but the reality is, there's not a "born difference" and the ish talkin should all just be fun-and-games -- People, regardless of race, religion, nationality, whatever, can do what they can do and can't do what they can't do... Race, skin color, nationality, [any other bs "born better" variable here] doesn't matter, because it's been proven time and time again if people of any race, nationality, religion, [whatever] take the time to look and actually think a bit, none of that ish matters a bit.

I'm currently trying to figure out what the offending site itself gains by redirecting links that will presumably be clicked by their own human users. Won't they get mad? I'd be plenty ticked off if I went to the garden-supply store, bought a sack of steer manure and took it home only to find it full of rose petals instead.