As stated in Bhagavad-gītā (7.20) :

kāmais tais tair hṛta-jṣānāḥ prapadyante ’nya-devatāḥ taṁ taṁ niyamam āsthāya prakṛtyā niyatāḥ svayā

“Those whose minds are distorted by material desires surrender unto demigods and follow the particular rules and regulations of worship according to their own natures.” Most people are interested in worshiping demigods to acquire powers. Each demigod has a particular power. For instance, the demigod Indra, the King of heaven, has power to shower rain on the surface of the globe to give sufficient vegetation to the earth. This demigod is described in the Vedas: vajra-hastaḥ purandaraḥ. Indra rules the water supply with a thunderbolt in his hand. The thunderbolt itself is controlled by Indra. Similarly, other demigods — Agni, Varuṇa, Candra, Sūrya — have particular powers. All these demigods are worshiped in the Vedic hymns through a symbolic weapon. Therefore it is said here, mantra-liṅgair vyavacchinnam. By such worship, karmīs may obtain the benediction of material opulence in the form of animals, riches, beautiful wives, many followers, and so on. By such material opulence, however, one cannot understand the Supreme Personality of Godhead.