I don't.
I really think the basic nature of humans is compassion, if it wasn't we would not have survived as a species. There would be no empathy, no altruism, no community spirit, no maternal instincts. They are all part of our nature.
We don't need a god to tell us to love our children, don't need a god to know that helping others feels good, don't need god to know how to love, to care, to nurture.
If all there is to life is life, would I be happier being an evil bastard, taking what I want, raping, killing etc... or would I be happier being compassionate and nurturing and receiving the same back? Kind of easy really.