Morality exists independent of God.
Don't believe me?
If Jesus came back to Earth on the day the OJ verdict was read, and said "Orenthal is my best pal. Them bitches had it coming," would that make OJ innocent? Would it make him a good person?
Right and wrong were not given to us by a deity and they are not subject to the whims of any being, human or supernatural.
How do you know that?
And what if someone has different ideas about what's right and wrong than you do?