It's just part of the territory. It seems like a lot of forums have a couple of people who think it's their job to bark at newcomers. I've seen the same kind of behavior at Christian and Muslim forums, they just tend not to use the expletives...and somehow still manage to make it sound nastier than 'fuck off, you ignorant asshole'.
I think all you can do is stick to the conversation you're having with the person if they stick around. Freethinkers tend to reject the very concept of there being such a thing as a word that's bad and shouldn't be spoken or written. I agree with that sentiment, but 'curse words' get part of their impact from shock value, so I try not to overuse them, especially in print. It's an interesting phenomenon that someone else can work up the atmosphere around them into a blue haze without detracting from someone else's ability to verbally hit harder when they want to by swearing judiciously.
I think all you can do is stick to the conversation you're having with the person if they stick around. Freethinkers tend to reject the very concept of there being such a thing as a word that's bad and shouldn't be spoken or written. I agree with that sentiment, but 'curse words' get part of their impact from shock value, so I try not to overuse them, especially in print. It's an interesting phenomenon that someone else can work up the atmosphere around them into a blue haze without detracting from someone else's ability to verbally hit harder when they want to by swearing judiciously.