How do you distinguish between right and wrong or is there a difference?

It's an odd and interesting question to me, because it seems that many religious people somehow believe that once one turns away from religion, one no longer has morals.
To which I can't help but reply, "Wait... what?!"
Though I no longer believe in the concepts of good, evil, and sin, I still know the difference between right and wrong. Choosing to do wrong will result in hurtful or bad consequences to others/myself, etc. That's why I choose to do right. And even though I now believe that my choices only affect this life, that's more than enough reason to keep doing right, it's as simple as that.