Well, that comes down to whether I feel obligated to help with Christianity's PR. When a group of Christians does something good, I link that all over FB and show them off and all that, but they're not any more legitimately-Christian than the Christians I dislike. Just because one kind of Christian makes a better neighbor than the other kind doesn't mean they aren't still both Christians.

I don't have to buy into the idea that the only real Christians are the dirtbags, but neither am I going to buy into the idea that the nice ones are the only "real" Christians, either, because they aren't.