If I knew of a certainty that there were justice in an afterlife, it would convince me even more that your god is merely your delusion.
I can see the appeal of this idea, that justice will come in the end to all, that the self-righteous will get the final and unavoidable last laugh. But the more I listen to the voices that clamor for this idea, the more certain I am that it is fantasy, and the more relieved I am that I don't have to worry about their prognostications. Perhaps there is a conception of a god who might be just who could pull of real final justice in the end, but if there is, no religion has yet imagined him.