Is God unjust ????????????????

No, God is not unjust. I'm sorry, but your argument is based on erroneous (human) reasoning. The notion that God "punishes" people for anything, really, is very human, and, therefore, (as you said) quite flawed. Eternal punishment cannot be justified, nor is it the case; unless, of course, you listen to humanoids, whose flawed minds created the very text that they hold as "The Word of God", anyway. God is the entire reason why "Just" can even be imagined (certainly not obtained by humans). He only has a problem when people do not use the 'Bio-supercomputer' they've been given, via evolution; or take as 'truth', some book that some other human wrote, and try to p it off as 'His word'; only then does He (metaphorically) weep.