PURPORT

Nanda Maharaja innocently thought, "Perhaps this boy Krsna formerly killed all these demons, and therefore in this life they are envious and are attacking Him. But Krsna is a fire, and they are flies, and in a fight between fire and flies, the fire is always victorious." Fighting is always taking place between the demons and the power of the Supreme Personality. Paritranaya sadhunam vinasaya ca duskrtam (Bg. 4.8). Anyone who is against the control of the Supreme Personality of Godhead must be killed, life after life. Ordinary living beings are subject to karma, but the Supreme Personality of Godhead is always victorious over the demons.