Religion in India is significantly different from Christianity. By the fourth century, Christianity had established a fairly stable canon of sacred literature. Not long after that, two institutional churches, the Catholic and Orthodox churches, came to dominate all Christian doctrine. There were, of course, heterodoxies that arose and variations within these churches, but they were, by and large, insignificant variations that never took hold. The Protestant Reformation did manage to create new, lasting theological doctrines, but again, the differences were slight, at least in comparison to the differences that one finds in the religious experience of India.
In Vaisnavism, Saivism and Minor Religious Systems, Ramakrishna Gopal Bhandarkar gives a dense account of a huge number of religious systems that arose in the course of India's long history. Indian religion has its roots in the ancient Vedas and came to a philosophical apex with the Upanishads. These texts were filled with numerous and contradictory theological and cosmological doctrines. They simultaneously portray a pantheon of countless gods along with views of God as both transcendent and immanent in the world. The concept of incarnations and avatars helped to make sense of these contradictions, but one must see the Vedas and the Upanishads as a collection of contradictory religious and spiritual insights written by numerous authors over many centuries. They are early drafts of the religious and spiritual insights that India has been interpreting and revising to this day. Two strands of thinking have, however, gained prominence: Vaisnavism and Saivism.
Bhandarkar's account of the history of Vaisnavism begins in the latter half of the first millennium B.C.E. During this time, Buddhism and Jainism arose in the east, while in the west theistic systems became popular, particularly one devoted to the worship of Vasudeva. Bhandarkar highlights references to Vasudeva in the Vedas, Upanishads, and the Bhagavadgita. In time, Vasudeva became identified with a Narayana, a supreme being that evolved from the early concept of Nadayana, the "resting place or goal of men." Vasudeva also came to identified with Vishnu, a rather minor god in the Vedas that appears supreme in later literature. Thus Vaisnavism came about as a combination of "streams of religious thought, namely the one flowing from Vishnu, the Vedic god at its source, another from Narayana, the cosmic and philosophic god, and the third from Vasudeva, the historical god." From that time, a wide variety of systems have emerged, among the most important is the worship of the Cowherd God, Gopala-Krishna.
In the eighth century, Samkaracarya and his followers began promoting a doctrine of spiritual monism and world-illusion. This was seen to be in conflict with Bhakti, or the love of God, which Vaisnavism required. In succeeding centuries, more pronounced and fanatic version of Bhakti evolved in which a "single-minded and devoted love of God" became necessary for attaining eternal bliss.
Bhandarkar observes that Vaisnavism celebrated God in his beneficent form, "The lovableness of the works of God, his greatness and majesty and his mysterious nature are...matters that strike the mind of man; and these appear to have operated in bringing Vishnu into prominence. What contributed to the formation of Vaisnavism were the appearances and occurrences which excited love, admiration and a spirit of worship," but these are not the only sources for the theological inspiration. Bhandarkar also writes, "Many are the occasions in the life of man, which excite fear; there are epidemics and other diseases, poisons, serpents, storms, thunderbolts and wild and awful scenes, and consequently the god who brings on these occasions and protects when appeased will be thought of oftener then other gods." Fear is the sentiment behind this theology and it is the god Rudra-Shiva and Saivism that evolved from it.
Rudra makes appearances in the earliest of the Vedas, the Rig Veda, and unlike Vishnu, is a relatively important god. There and in subsequent literature, he is given additional names including Shiva. According to Bhandarkar, the Saiva system has three principles and four parts. The principles are the lord (Pati), the individual soul (Pasu), and fetters (Pasa). The parts knowledge (Vidya), action (Kriya), meditation (Yoga), and conduct (Carya). Vidya provides an account of the three principles and amounts to a set of theological and metaphysical doctrines, along with a description of the fetters which inhibit us from salvation. The actual spiritual path of Saivism involves the religious ritual and yogic practices, and moral discipline outlined in the last three parts. Much of the section on Saivism includes descriptions of the practices of various Saiva sects.
In the final pages of Vaisnavism, Saivism and Minor Religious Systems, Bhandarkar revisits the debate over the immanence or transcendence of God. His conclusion is that the distinction is not relevant to Indian religions. For both Vaisnavism and Saivism, God is understood to be both immanent and transcendent. His explanation as to how both can be true is cryptic; however, one might begin to understand this by thinking of the individual self as a deluded and alienated fragment of the Godhead. Our delusion and alienation is what makes God transcendent relative to our earthly circumstance. Our task in life is to overcome the fetters that separate us from the Godhead and realize its immanence.