First let's make it clear than I'm not talking about an afterlife, just about a rewarded and punished afterlife according to your actions during this life. I think the idea of some people being rewarded and some punished is basically a moral equation in order to balance and comfort ourselves...
This statement limits the grounds upon which we can talk. You are not talking about a specific afterlife, merely trying to reflect upon the idea of any reward system in any concept of an afterlife. Of course if one merely wants to look at this small part (reward system) and try to determine a full meaning (why we believe in an afterlife) they are going to yield a result which doesn't really tell us much.
A belief in an afterlife is not altogether a selfish act, that is, it is not for us just to feel better and comfort ourselves. However it depends on how you look at the complete picture of an afterlife. Someone who believes in reincarnation or someone who believe in a resurrection of the spirit for instance, this makes a big difference when you try to see answers. However in your post it seems you just want to consider the reward system alone without defining which afterlife you are talking about. As soon as you want to discuss which religion you are talking about then you must look at the entire picture of the religion to yield intelligent conclusions.
If one says "Why believe in an afterlife?" And answer it with "Because of a reward system! that makes us feel good", what are you really trying to say?
because we don't think it's fair that a cute and nice child could die so young while so many criminals and corrupted people are living their lives like kings or just getting 5 years in prison to get out in 2.
Injustice happens always but we don't feel better about it simply by believing in an afterlife or think about a reward system in afterlife. If someone says, oh don't worry that murder, God will get revenge for us in the afterlife! How evil is that thinking??? How can that better yourself! Certainly there are people do actually think in this negative fashion, but we know that is not an intelligent way to live your life. Love is what cleanses our minds not believing in a reward system in an afterlife.
Just take a look at laws and general thinking on gay or black people, or even women 50 years ago, not to mention things like sacrifices, punishments and the way sex or drugs were considered 3000+ years ago; and of course, morality is not consistent through nature in the least either. So how could we be rewarded/punished for eternity because of laws that are constantly changing even during our own life time?
You are assuming that you should understand the scales in of judgement, no one should dare to think about it, so it is not our responsibility to try to tell you how people will be judged. It is pointless thinking imo. If one thinks about the scales then all their actions will be insincere and merely for selfish gain. We have a life to live, to consider our rewards in an afterlife makes us forget about our life now plus makes our actions quite insincere!
Compared to eternity our lives, no matter how long they may be are nothing, and our minds simply cannot comprehend what an infinite time means.
You assume that we will exist in eternity in our physical blood and bone bodies we have now. This might not be the case and perhaps a different state will allow us to percieve what our imperfect minds can understand. After all we all know that we use an extremely small % of our brain power.
With your candy story you are assuming that we have only one chance and can never turn a new leaf. Of course this is untrue and someone may repent on their deathbed. However I really believe sincerity is key. Anyone can play a game and look good, but is it truly in their hearts? Only God can know that for sure. It is useless for us to speculate. But certainly there is not just one moment in our life which condemns us.
You don't see it in action in Business, many successful businessmen and women failed many times, just look at KFC's Colonel Harland Sanders story, or Thomas Edison experiments in the light bulb. Or at school, they don't give you one test in grade 1 and decide, right you will go to university or not. So why expect this when it comes to a judgement in an afterlife? If we consider God to be perfect (even atheists can understand that this must be a requirement of a God), then his judgement will be also perfect and no one will feel hard done by.
Armed with this easy logic you can move on and live your life without letting those scales cloud your thought. If you think arguing about the scales is intelligent then I would wonder why you ignore that God is perfect. If you do not believe in a God then why use the scales as a measuring stick to disprove or cast negative light upon the topic?
"I cannot conceive of a God who rewards and punishes his creatures, or has a will of the kind that we experience in ourselves. Neither can I nor would I want to conceive of an individual that survives his physical death; let feeble souls, from fear or absurd egoism, cherish such thoughts."
This is assuming that one knows the scales of justice, Einstein was known to try to find solutions to the impossible.
Think of heaven and hell like this. Hell is an absence of God, Heaven is the presence of God. If God doesn't interest you then you have nothing to worry about either way right? You will either get your way, or learn something new.