vrulovwrath

Once there was Kain who killed his brother Avel and god cursed him to walk the earth forever. Was this punishment fair or not? Was god fair with Kain or it acted a litle bit too strict? So many people kill so many others today and god accepts them in heven if they admit their sins and stuf like that and ask for forgivenes. Why did it punish Kain like that?
Tell me your opinion.