I think that it's best to not respond to blatantly mean people altogether.
Bitterness knows no creed; on Y!A I've seen nasty attitudes from all sides and I've seen loving attitudes from all sides. In the middle there is humor which is always refreshing.
The same as for life outside of Y!A.
I have some awfully rude Christians in my life- do I ignore them? Certainly not. I just don't respond to their nasty attitudes, I just try my best to love them.
Don't give people such power over you. You choose whether or not to get angry over someone else's words. Don't dignify it with a response then, or, don't take it to heart. I know it's easier said than done but really, do they truly know you, like your closest loved one does? No. Do they think about your safety or think of you during quiet times, of course not. So don't let such small-minded remarks get the better of you. Pour your energy into positivity and loving your neighbor. It's wiser to turn the other cheek than to mince words. :)
You have enough integrity and self respect to know who is worth your time and energy; respond to people who are and just leave be those who are not.
I'm not easily offended by many of the same things I guess. I think it's worse when I see someone else who claims to be a Christian telling another person to go to Hell or making crass judgments against another person. No matter how ugly someone is they don't deserve to be treated that way; and people who know God's love should know better.
People are mean because they are hurting, remember that. It's Psych 101. Hurt knows no creed either. All humans have the ability to feel joy and to feel pain. Does the joyful heart inflict pain or love on others? Does the bitter heart inflict love or pain on others? People will deny it but that's the truth, there is no other reason to be bitter, regardless of personal beliefs.
Try to remember that next time someone pushes your buttons, just extend love, grace and mercy; and move on.
There may come a day when you are hurting, when the shoe is on the other foot and you are being ugly to other people. Would you rather fling insults back and forth, or, would you rather have someone with the compassion to understand that your life isn't "peachy" and then extend grace and love to you?
Peace. :)