“When the Great Scorer comes to mark against your name, He writes not that you won or lost, but how you played the Game.” Grantland Rice
Even though I may question or even not believe in a heaven, hell or an afterlife, I will live my life in a manner that is in keeping with how I want to be treated by others. It is not because I want to get into heaven or have a better experience in the afterlife, but simply because it is the right thing to do. I do not believe someone should be good only because they are afraid of going to hell, they should be good because it is what they want to do. Living in fear of your actions is not how I want to live my life. I would prefer to live my life the way I feel it should be lived and face the consequences, if there are any, rather than to live and act in fear of the consequences.
I do believe that any harm or ill will I do to others may come back to haunt me, not in an afterlife, but here, while still living. I will do my best not to intentionally harm others. If there comes a time where I do harm someone, I will do my best to reverse the damage, or to make retributions.