Arjuna is an accepted devotee of the Lord, so how could he not believe Krsna's words? The fact is that Arjuna is not inquiring for himself but for those who do not believe in the Supreme Personality of Godhead or for the demons who do not like the idea that Krsna should be accepted as the Supreme Personality of Godhead; for them only Arjuna inquires on this point, as if he were himself not aware of the Personality of Godhead, or Krsna. As it will be evident from the Tenth Chapter, Arjuna knew perfectly well that Krsna is the Supreme Personality of Godhead, the fountainhead of everything and the last word in Transcendence. Of course, Krsna also appeared as the son of Devaki on this earth. How Krsna remained the same Supreme Personality of Godhead, the eternal, original person, is very difficult for an ordinary man to understand. Therefore, to clarify this point, Arjuna put this question before Krsna so that He Himself could speak authoritatively. That Krsna is the supreme authority is accepted by the whole world, not only at present, but from time immemorial, and the demons alone reject Him. Anyway, since Krsna is the authority accepted by all, Arjuna put this question before Him in order that Krsna would describe Himself without being depicted by the demons who always try to distort Him in a way understandable to the demons and their followers. It is necessary that everyone, for his own interest, know the science of Krsna. Therefore, when Krsna Himself speaks about Himself, it is auspicious for all the worlds. To the demons, such explanations by Krsna Himself may appear to be strange because the demons always study Krsna from their own standpoint, but those who are devotees heartily welcome the statements of Krsna when they are spoken by Krsna Himself. The devotees will always worship such authoritative statements of Krsna because they are always eager to know more and more about Him. The atheists, who consider Krsna an ordinary man, may in this way come to know that Krsna is superhuman, that He is sac-cid-ananda-vigraha—the eternal form of bliss and knowledge—that He is transcendental, and that He is above the domination of the modes of material nature and above the influence of time and space. A devotee of Krsna's, like Arjuna, is undoubtedly above any misunderstanding of the transcendental position of Krsna. Arjuna's putting this question before the Lord is simply an attempt by the devotee to defy the atheistic attitude of persons who consider Krsna to be an ordinary human being subject to the modes of material nature.