Start with the fact that humans are naturally moral beings. We want to get along with our fellows. We care about our families. And we feel that we should put our hands in our pockets for the widows and orphans. This is not a matter of chance or even of culture primarily. Humans as animals have gone the route of sociality. We succeed, each of us individually, because we are part of a greater whole and that whole is a lot better at surviving and reproducing that most other animals.
Michael Ruse has gone quite a ways towards establishing a one world atheist religion—the Allunimati.
Too much, too paranoid, too conspiratorial, too hyperbolic you say? Consider his words (emphasis added):
…only by recognising the death of God can we possibly…behave properly to our fellow humans and perhaps save the planet…