Man, I love discussions like this, even if I don't have much to contribute to.
Okay, so I've got a question, if right and wrong is subjective, then was the holocaust wrong? To us it was wrong, but to Hitler it was right, but I don't think that anyone would argue that it was "right".
I also think that religion does have to become involved, because I believe that the "conscience" that we have inside of us is from God. If there were no higher power, then we're just a bunch of life forms, and there is no good and evil, only what we believe to be right and wrong. Without religion in the picture, then yes, right and wrong are subjective.
Sorry if I wasn't very clear on my points or if didn't add much to the discussion, I'm still new to thinking about this topic. I suggest reading the first few(at least 3) chapters of C.S Lewis's
Mere Christianity. He makes a great argument for a universal moral code in humans.
I believe that each person has something inside of them that gives them the ability to tell that difference: call it a conscience.
But Reaves, where does that conscience come from? ( I'm not trying to prove a point or anything here, I genuinely want to know what you think)