Gentle devotees of the Supreme Personality of Godhead know perfectly well who is God and who is not. Nondevotee impersonalists, however, who have no idea what God is and who never offer prayers to the Supreme Personality of Godhead, are always interested in accepting a human being as God and offering such prayers to him. This is the difference between a devotee and a demon. Demons manufacture their own gods, or a demon himself claims to be God, following in the footsteps of Ravana and Hiranyakasipu. Although Prthu Maharaja was factually an incarnation of the Supreme Personality of Godhead, he rejected those praises because the qualities of the Supreme Person were not yet manifest in him. He wanted to stress that one who does not actually possess these qualities should not try to engage his followers and devotees in offering him glory for them, even though these qualities might be manifest in the future. If a man who does not factually possess the attributes of a great personality engages his followers in praising him with the expectation that such attributes will develop in the future, that sort of praise is actually an insult.