I've recently been engaged in an interesting dialogue at Secular Right a blog for political conservatives who reject theism. The discussion resulted from a post there that discussed the fact that our concern for people diminishes as our (cultural, genetic, geographical) distance from them increases. My point was that on secularist assumptions there's no reason why this should be otherwise. You can have an obligation to care about others or you can have atheism, but you can't have both.
Check out the post and the exchange here. I go by my nickname Dick in the comments section.
RLC