Would you bite the apple that gave knowledge of good and evil? Read on.
We find ourselves alive and conscious. What shall we do with our lives? Beware "fishers of men". If we demand that someone else supply us with a purpose, someone else may DO just that. Purpose is ours to choose.
There is a natural "default" purpose, which we may choose if we like. We all have parents, as did they, back to the beginning of life. Every one of our ancestors had children. Health is the ability to survive; the goal favored by natural selection is "promote the health of your family." We are all members of Darwin's family, all kin from the beginning of life.
The Good is that which leads to health, The Right is that which leads to peace. If you want to maintain peaceful and cooperative relations with your neighbors, don't kill, steal, lie, or break agreements. As Shakespeare wrote, "It needs no ghost, Milord, come from the grave, to tell us this." If you value anything, value other humans, for they are the only help you will have in times of trouble.
Fairy-tales about the supernatural are not necessary to give meaning or purpose to life. Meaning is the story we choose to join. Instead of seeking a ticket to Heaven by being an obedient slave on Earth, we can gain meaning by taking a positive role in history, seeking to make this Earth a better place.
The Godless Universe is vast and wondrous, and more than enough. We have loved the stars too fondly to be fearful of the night.