I think because it is difficult to reconcile a loving father or God with the concept of an eternal state of suffering; it is a depressing and bleak vision. Christianity is the only organized religion that believes in a permanent separation between God and his creation. Judaism and Islam both believe in hell as only a temporary punishment. Muslims believe that God is so compassionate that he eventually forgives sinners and lets them out of hell until it is eventually empty. Jewish people believe it is only a temporary place before the soul joins God in the light.