The Atheist Perspective

The nature of the world, human beings, and social systems, combined with the universal human desire to live a fulfilling life.

This is formally demonstrated in Richard Carrier, "Moral Facts Naturally Exist (and Science Could Find Them)," in The End of Christianity, pp. 333-64, 420-29. For further discussion, see Moral Ontology and Goal Theory Update and Richard Carrier's Sense and Goodness without God.