LOL, you are talking as if the only bad thing that a human can do is murder…There are many awful crimes, and I was referring to every shameful act you can think of not only killing and it is not attached to certain sect.
No, I never said that. And I agree that either theist or non theist would do such horrible acts due to the sickness in their minds. But tell me if there was no worldly punishment for any crime, who would not still commit crimes? The believer in afterlife, or someone who doesn't believe in it?!
And please don't tell me human compassion and so on....As we all can see the horrible wars all over the world, and we see no compassion or anything like that. In fact one self is more important than that compassion (in case that person didn't reinforce that passion through Divine Justice).
My point is that belief in afterlife would give those oppressed the strength to accept their fate in this limited life, and try to do their best to live honorable life in the next life. That belief is not a "wishful-thinking" it is a certainty: Belief in God + Good deeds=Paradise.
First of all, I want to express my deep sorrow and sympathy with the Haitians. In fact; earthquakes and such universal phenomena are signs and indications of God's Majesty, it is a reminder for us that no matter the scientific level we reached, we are still within His power and omnipotence. They are also tests of faith, helpfulness, brotherhood, sincerity and so on of humans. They are not simply a sort of punishment, but rather a test.
I didn't know that

…But would you please elaborate on the Platonic Justice?
And because we are humans, we should adhere to justice in all cases. We have to believe in a just life after a life full of hypocrisy and oppression, with a slight ray of justice.
Well, we should first define "ethical egoism" to know whether what I'm saying is modified or not.
"Ethical egoism (also called simply egoism)[1] is the normative ethical position that moral agents ought to do what is in their own self-interest."
Ethical egoism
Why is it modified? Because a believer is doing something against his own interest in this life (ethical altruism)…But due to Divine Justice, his good deeds will not go with the wind. Instead, he would be rewarded for that (modified ethical egoism).
I think it is quite clear that the two concepts are kinda different.
Sorry, it is not intentional; I didn't see your question, really
They key word in your question is "Believer" that's the difference. A believer would do that and waiting the reward in the afterlife, while a non-believer would be waiting it in this life. And both of them would get what they wanted (The Divine Justice)!