I've been struggling for the words, and it feels like it too many or too few.
It is based on who we really are. If the habit is to focus more on self, then yes, of course, that person will be unsympathetic. If the focus is more on others, then you'll find the opposite to be true. Belief is in how we interpret it. The big difference I've found is that, especially in this area, religion is guaranteed to truly change your nature to "awesome" when really, it's just throwing a new tablecloth over the same broken-down card table and claiming it's brand new.
I can say that "Justice is not part of the design of the universe" and have one person think I'm a barely resisting being a serial killer and the other see that just because life isn't fair doesn't mean that I can't try to change that.