Hinduism, being a dynamic religion caters for all types of people, high thinkers and common people as well. High thinkers can think of or conceive God as Impersonal (without attributes/form) whereas common people with attributes, i.e. they can think of God as being Personal. Concerning the Personal aspect of God, Hinduism believes in the Hindu Trinity where we have Brahma as the Creator, Vishnu as the preserver and Shiva as the Destroyer. Since Vishnu’s function is to preserve. Whenever the existence of the world is threatened by evil forces, He incarnates on earth in human or non-human form to re-establish the balance between righteousness and unrighteousness. In the Bhagavad Gita Krishna says:
“Whenever righteousness declines and unrighteousness prevails, I manifest Myself; for the protection of the good, for the destruction of the wicked and for the establishment of righteousness, I am born in every age” – B.Gita, IV.7&8
Shri Krishna is considered to be one of the incarnations of Vishnu; whatever He says in the Gita is authoritative.
The definition of the term avatara is “the descent of God on earth in either human or non human form to protect dharma”. The concept of incarnation is not Vedic in nature, it became well pronounced during the Epic Age and the period of the Puranas where Vishnu became popular because of His incarnations. The Epic Age was different from the Vedic Age but despite this the Vedas and Vedic institutions were still noted, the various incarnations helped to safeguard these. According to the Bhagavata Vishnu has twenty-two incarnations, but the most popular view is that He has ten incarnations only: (1) Fish or Matsya, (2) Tortoise or Kurma, (3) Boar or Varaha, (4) Man-Lion or Narsimha, (5) Dwarf or Vamana, (6) Rama with the axe or Parashurama, (7) Rama the Perfect Man, (8) Krishna, the philosopher king, (9) Buddha, the preacher of peace and (10) Kalki, the final destroyer. So far nine incarnations are said