This is a verse from the Padma Purana. Visnu-bhaktas, or devotees in Krsna consciousness, are known as devas (demigods). Atheists, who do not believe in God or who declare themselves God, are asuras (demons). Asuras always engage in atheistic material activities, exploring ways to utilize the resources of matter to enjoy sense gratification. The visnu-bhaktas, Krsna conscious devotees, are also active, but their objective is to satisfy the Supreme Personality of Godhead by devotional service. Superficially both classes may appear to work in the same way, but their purposes are completely opposite because of a difference in consciousness. Asuras work for personal sense gratification, whereas devotees work for the satisfaction of the Supreme Lord. Both work conscientiously, but their motives are different.