Tantra is an esoteric (occult) religious tradition that originated in Hinduism but also exists in Buddhism and other Asian religions. Many orthodox Hindus regard it with suspicion or outright disdain because of its disregard for, or outright rejection of, the primary Hindu scriptures, the Vedas. It nonetheless does hold to many of the core Hindu doctrines, but with its own twists.
For example, while it agrees with Advaita Vedanta that Brahman is essentially Being, Awareness, and Bliss (called Sat-Chit-Ananda in Sanskrit), that Brahman is all there is, and that the world is maya or illusion, it defines maya differently, not merely as illusion but as a real operation within the nature of Brahman. The true essence of the world and souls is Sat-Chit-Ananda, but they are nonetheless real. Maya therefore consists of Brahman’s evolution from undifferentiated oneness into the multiple forms of the world (prakriti) and also of Brahman’s involution from the world back into undifferentiated oneness. Swami Nikhilananda, founder of the Ramakrishna-Vivekananda Center of New York, expounds on this important aspect of Tantric belief:
Evolution or the “outgoing current” is only one half of the functioning of Maya. Involution, or the “return current”, takes the jiva [i.e., soul] back towards the source or root of Reality, revealing the infinite. Tantra is understood to teach the method of changing the “outgoing current” into the “return current”, transforming the fetters created by Maya into that which “releases” or “liberates”. This view underscores two maxims of Tantra: “One must rise by that by which one falls” and “the very poison that kills becomes the elixir of life when used by the wise.”14
Tantra yogis have many ritual practices that seek to embrace the dualities of prakriti (as best represented by the god Shiva and his consort Shakti) and unite them, thus transmuting the energy of evolution into the energy of involution, which they believe will result in their own enlightenment. This approach calls for participating in activities that are normally renounced by Hindus seeking enlightenment, such as eating meat, consuming alcohol, and having sexual relations. Tantrists believe that if they can maintain a transcendent state of consciousness throughout such activities they will unite polar energies and so transcend maya and prakriti.
In the Hindu religion tantra yoga consists of two major approaches: the Dakshinachara Path (know as right-handed Tantra) and the Vamachara Path (known as left-handed Tantra). Right-handed tantra typically would only symbolically, and not actually, engage in the deeds of the flesh associated with its ritual. Left-handed tantra, on the other hand, not only involves actual sex, alcohol, and drugs, but also has been known to involve black magic and all kinds of debauchery and criminal acts, including child sacrifice.15