Q. What actions can make one a Demigod?
A. By perfoming lots of pious activities,one gets promoted to the heavenly planets.
Those who are simply official students of the Vedas become more interested in offering sacrifices to the different demigods like Indra and Candra. By such endeavor, the worshipers of different demigods are certainly purified of the contamination of the lower qualities of nature and are thereby elevated to the higher planetary systems or heavenly planets known as Maharloka, Janaloka, Tapoloka, etc. Once situated on those higher planetary systems, one can satisfy his senses hundreds of thousands of times better than on this planet.
Bhagavad gita-As It Is( 9.18)
Those situated in the mode of goodness gradually go upward to the higher planets; those in the mode of passion live on the earthly planets; and those in the abominable mode of ignorance go down to the hellish worlds.
In this verse the results of actions in the three modes of nature are more explicitly set forth. There is an upper planetary system, consisting of the heavenly planets, where everyone is highly elevated. According to the degree of development of the mode of goodness, the living entity can be transferred to various planets in this system. The highest planet is Satyaloka, or Brahmaloka, where the prime person of this universe, Lord Brahmä, resides. We have seen already that we can hardly calculate the wondrous condition of life in Brahmaloka, but the highest condition of life, the mode of goodness, can bring us to this.
Bhagavad gita 9.25
Those who worship the demigods will take birth among the demigods; those who worship the ancestors go to the ancestors; those who worship ghosts and spirits will take birth among such beings; and those who worship Me will live with Me.
If one has any desire to go to the moon, the sun or any other planet, one can attain the desired destination by following specific Vedic principles recommended for that purpose, such as the process technically known as darsa-paurnamasi. These are vividly described in the fruitive activities portion of the Vedas, which recommends a specific worship of demigods situated on different heavenly planets. Similarly, one can attain the Pita planets by performing a specific yajna. Similarly, one can go to many ghostly planets and become a Yaksa, Raksa or Pisaca. Pisaca worship is called “black arts” or “black magic.” There are many men who practice this black art, and they think that it is spiritualism, but such activities are completely materialistic. Similarly, a pure devotee, who worships the Supreme Personality of Godhead only, achieves the planets of Vaikuntha and Krishnaloka without a doubt. It is very easy to understand through this important verse that if by simply worshiping the demigods one can achieve the heavenly planets, or by worshiping the Pitas achieve the Pita planets, or by practicing the black arts achieve the ghostly planets, why can the pure devotee not achieve the planet of Krishna or Visnu? Unfortunately many people have no information of these sublime planets where Krishna and Vishnu live, and because they do not know of them they fall down. Even the impersonalists fall down from the brahmajyoti. The Krishna consciousness movement is therefore distributing sublime information to the entire human society to the effect that by simply chanting the Hare Krishna mantra one can become perfect in this life and go back home, back to Godhead.