Richard Dawkins

we are likely to mistake a shadow for a burglar; we are unlikely to mistake a burglar for a shadow. We have a bias towards seeing agents, even when there aren’t any. And religion is all about seeing agency all around us.

Useless or superstitious beliefs, like the need to pray five times a day, or the need to sacrifice a goat to cure malaria, get passed on as a byproduct of sensible beliefs – or rather, as a byproduct of child brains being shaped by natural selection to believe parents, teachers, priests and other elders. And that is favoured by natural selection, because much of what elders tell children is sensible.

Suppose two nations have different religions. One has a warlike god, like Yahweh/Allah. Or
like the warlike gods of the Vikings. The priests of such gods preach the virtues of courage in battle. They teach, perhaps, that a warrior who dies a martyr’s death will go straight to a special martyrs’ heaven. Or will go straight to Valhalla. They might even promise beautiful virgins in heaven to those men who die fighting for the tribal god (do you, like me, feel sorry for the poor virgins?). The other nation has a peaceful god or gods. Their priests don’t advocate war. They don’t preach heavenly bliss for those who die fighting. Maybe they don’t preach any kind of heaven at all. All other things being equal, which nation will have the bravest warriors? Which nation is more likely to conquer the other? And therefore, which of the two religions is most likely to spread? The question answers itself. It is a matter of history that the spread of Islam, from Arabia throughout the Middle East and the Indian subcontinent, was due to military conquest. And the same goes for the spread of Christianity by the Spanish conquerors in South and Central America

it’s safe to say you’ve drunk some of Julius Caesar’s pee.