I've heard people say, doing good only for the reward isn't good at all. This seems deeply strange to me. Let me explain using a hyperbolic metaphor:

Let's say St. Peter, before manning the Pearly Gates, is chatting with God about who should get into heaven. God says, "Doing good just for the reward is selfishness, a terrible vice, so if someone does a lot of good, and two thirds of their amazing life-saving charity was for the reward of being known as very charitable, and one third would have been done in silence and was a true expression of graciousness and warmth – that person should go to hell, can't you see their selfishness outweighs their warmth? It's two to one, Peter, it's obvious."

Peter takes off his glasses, and rubs the bridge of his nose. God doesn't have to pour over the records every day, he knows what humanity is like but he doesn't know, ya know?

"It is obvious, yes. But heaven is more than a place to collect cool people. It's an incentive, you see – otherwise we wouldn't tell people about it. There's plenty we keep secret, of course. We haven't told any of them about Mega-Ping-Pong, for instance, it's too awesome to share. But the idea with an incentive system is, we can water down heaven a tiny little bit to achieve a big change in outcomes on Earth."

God looks at Peter, knowingly. "Water down heaven? That doesn't sound like your job, Peter."

"There's a duality of purpose to my work. The cat's out of the bag, people know we judge them. There's an enforced choice, now, between incentives and pure tests of moral character. To choose against having incentives, letting people in only because of virtue and never just good deeds, balances your preferences for heaven and preferences for earth entirely on one end – it expresses a perfect apathy to conditions of the world in comparison. Because with incentives you could change the world, and only by letting people in who are still very virtuous – they did help people – just not quite as perfectly good."

God sighed. "But heaven is Infinitely Beyond Man! You know this, it's in those welcome packets you hand out every day. Surely, that's the appropriate weighting?"

"The issue is that before people get here, they don't know precisely who you are. Every detail couldn't possibly be filled in – Infinitely Beyond Man is no understatement. So they have an extremely limited tool set with which to guess. And many, perhaps the ones best suited to their World Beneath Heaven, have learned to only cooperate with those that share their values. Many have decided, unlike the myths of callous and hate-filled Gods, given offerings of executed babies, they would instead only serve the interests of someone who supports good as they know it. Which means, someone who supports good in their world. They are not all charitable people, but they are people who understand the value in charity. Not everyone has virtue, but many recognize it. To see an innocent child tortured and decide it is Infinitely Beneath Consideration is a monstrous act, to them. You could find a great deal of virtuous people set against your path instead of advancing it."

"Doesn't mean I want to invite them into Heaven and spend time with them."

"Ah, but you see how even a maximally disinterested-in-Earth policy might dilute Heaven as well, then. Because we aren't an Eldrich place, not to those who get invited here. There's a continuity, that's the whole point. So even if our goals are a horror, turning a blind eye to the torture of innocents, even if we are a Horror Beyond The Wits Of Man, we should still basically run it like we were trying to give proper incentives to people and push their world to be a better place."

"Okay, fine, but just this one universe. And don't reward those Opera House charities, I don't like people screeching my name."

I'm not sure we should be more strict in your piety and judgment that that. We have to live here, after all.