Brave New World
How we cite our quotes:
"Do you remember that bit in King Lear?" said the Savage at last. "'The gods are just and of our pleasant vices make instruments to plague us; the dark and vicious place where thee he got cost him his eyes,' and Edmund answers – you remember, he's wounded, he's dying – 'Thou hast spoken right; 'tis true. The wheel has come full circle; I am here.' What about that now? Doesn't there seem to be a God managing things, punishing, rewarding?"
"Well, does there?" questioned the Controller in his turn. "You can indulge in any number of pleasant vices […] and run no risks of having your eyes put out." (17.34-5)
Mustapha refuses to take into account any conception of divine justice or the afterlife. If there are no punishments during life, in Mustapha's mind there must be no punishments at all.
"The gods are just. No doubt. But their code of law is dictated, in the last resort, by the people who organize society; Providence takes its cue from men." (17.35)
Again, Mustapha represents religion as a purely invented, social construction used to keep people in line. Since the Controllers have hypnopaedia and soma to maintain order, religion just isn't needed.
"Christianity without tears – that's what soma is." (17.47)
This is a pretty explicit summation of what was previously subtle and nuanced. Mustapha said essentially the same thing – but with less obvious didacticism – in Chapter Three.