God exists, there is an afterlife, and you will pay for your sins in this life. Some or all of that may be true, or not. But what is definitely true is that if you are reading this then you are alive and your words and actions affect others. Maybe there are consequences to harmful actions towards others, but even if there isn't it doesn't make it alright to hurt someone else. So, my personal philosophy is, do unto others as you would have them do unto you. Not in the hope of eternal salvation or any reward, but IMHO when you help others you also help your own self image.