I find 99.9% of the time it's very friendly but there are a few who seem to try to stir trouble or take offence if someone or more than one person doesn't share their view. That's only natural that we won't always agree but we should be able to see the others point of view and respect that. I'd hate to meet said people on real life, I hope it's just the fact they can hide behind a keyboard and screen that they feel that they can be as rude and aggressive as they are.
Seems your best just to take a step back and left these people rant on. Don't rise to it and they'll soon get bored.