Vaishanavism is the religion devoted to the worship of Vishnu and his two chief incarnations, Rama and Krishna with their consorts. Its chief tenet is that of bhakti, or devotion to a personal god of grace, which some scholars trace back to varuna in the Vedas and to certain passages in the Upanishads. But the vedic origin is tenuous and has only recently been invoked to prove its priority, while in the Upanishads the worship of the godhead is only permitted as a concession to human weakness.
The Bhakti cult probably had a non-vedic genesis. Fragments of such a cult are scrappily discernible in the first and second centuries BC in the creeds of certain nonaryan tribes like the satvata. These early faiths seem to have become blended in the doctrines of the Pancharatra, sect, which embodied many of the ancient primitive features tribe intimately connected with vaishnavism were the abhira, who made significant contributions to the mythology of Krishna's early life.
Among the principal features of Vaishnavism were: its strongly antibrahminical and anti-priestly attitude, well exemplified in the works of the Maratha saints; its use of vernaculars, like Hindi, Tamil, Marathi, in place of Sanskrit; its emphasis on absolute faith, and complete and total self-surrender to god, its stress on devotion through image-worship and simple ritual rather than through knowledge or the intermediary of priests; and finally its development of its own form of ritualism, including caste marks etc.
The Chief landmarks in the history of Vaishnava literature are: Pancharatra Agamas of Shandilya and his successors; the composition of the Narayaniya, the Anugita and the Harivamsha, all now embodied in the Mahabharata. The sect was reinstated by Ramanuja who brought the soul back to Hindu Philosophy.
A catalogue of the great Vaishnavita personalities in religion are Ramanj, Nimbarka, Jayadeva, Lokacharya, Madhava, Deshika, Ramananda, Vallabha etc.