Being someone that doesn't believe in the superman in the sky, I have been asked several times how it is possible for me to know the difference between right and wrong. How can one possibly have a moral compass without guidance from a work of fiction and the fear of eternal damnation in a mythical hell if you do not conform?
Of course the over simplified answer from me to that over simplified questions is that I ask myself "how would I feel if the act in question happened to me or someone I know?" and then if that still doesn't answer my question I just follow laws that have been codified over hundreds of years.
As to the question of needing some sort of hellish place that some feel is required to keep one in line, I guess there is always the fear of being Bruno's prison bitch if I fail to follow those rules. That would be pretty hellish wouldn't it?