Considered normative tantric Saivism, Shaiva Siddhanta(Tamil:சைவ சித்தாந்தம்) provides the normative rites, cosmology and theological categories of tantric Saivism. Being a dualistic philosophy, the goal of Shaiva Siddhanta is to become an ontologically distinct Shiva (through Shiva's grace).
This tradition was once practiced all over India. However the Muslim subjugation of north India restricted Shaiva Siddhanta to the south, where it merged with the Tamil Saiva movement expressed in the bhakti poetry of the Nayanars. It is in this historical context that Shaiva Siddhanta is commonly considered a "southern" tradition, one that is still very much alive. The Tamil compendium of devotional songs known as Tirumurai, along with the Vedas, the Shaiva Agamas and "Meykanda" or "Siddhanta" Shastras, form the scriptural canon of Tamil Shaiva Siddhanta.
Shaiva Siddhanta encompasses tens of millions of adherents, predominantly in Tamil Nadu and Sri Lanka. Today it has thousands of active temples there and a number of monastic/ascetic traditions, along with its own community of priests, the Adisaivas, who are qualified to perform Shaiva Siddhantin temple rituals.
The name of the school could be translated as "the settled view (siddhānta) of Shaiva doctrine" or "perfected Shaivism." There are of course many other Shaiva doctrines, and so it may seem odd that this particular one should have been known by a name that makes such a large claim, but widespread epigraphical and literary evidence suggests that this is because it simply was the dominant school of Shaiva liturgy and theology for a long period and across a wide area. Early works of the school do not appear to use the label Śaivasiddhānta: one the earliest datable attestations of the label is probably that in the eighth-century Sanskrit inscription carved around the central shrine in the Kailasanatha temple in Kancheepuram.
Early Siddhanta 
The Siddhanta tradition, like Kashmir Shaivism and Kaula, differs from the Vedic and Puranic worship of Shiva and also from the ancient Pasupati tradition by its adherence to texts called Agamas or Tantras, which lay down rites that may be performed by men of the first four varnas (women in these varnas played marginal roles) and describe a progressive, fourfold spiritual path of virtuous and moral living (charya), ritual (kriya), individual practice (yoga) and knowledge (jnana, vidya). The Siddhanta Prakashikā of Sarvātmasambhu refers to these Siddhanta Shastras as the "mantramārga" ("mantra way") which has been further elaborated by the modern scholars Flood and Alexis Sanderson in their research articles.
Saiva Siddhanta's original form is uncertain. Some hold that it originated as a monistic doctrine, espoused by Tirumular (date unknown). It seems likely to others, however, that the early Śaiva Siddhānta may have developed somewhere in Northern India, as a religion built around the notion of a ritual initiation that conferred liberation. Such a notion of liberatory initiation appears to have been borrowed from a Pashupata (pāśupata) tradition. At the time of the early development of the theology of the school, the question of monism or dualism, which became so central to later theological debates, had not yet emerged as an important issue.
Tamil bhakti 
|The twelve volumes of Tamil Shaivite hymns of the sixty-three Nayanars|
|Padal petra stalam|
|Padal Petra Stalam|
|Raja Raja Chola I|
From the fifth to the eighth CE Buddhism and Jainism had spread in Tamil Nadu before a forceful Shaiva bhakti movement arose. Between the seventh and ninth centuries, pilgrim saints such as Sambandar, Appar and Sundarar used songs of Shiva’s greatness to refute concepts of Buddhism and Jainism. Manikkavacakar's heart-melting verses, called Tiruvacakam, are full of visionary experience, divine love and urgent striving for truth. The songs of these four saints are part of the compendium known as Tirumurai which, along with the Vedas, Shaiva Agamas, and the Meykanda Shastras, are now considered to form the scriptural basis of the Śaiva Siddhānta in Tamil Nadu. It seems probable that the Tirumurai devotional literature was not, however, considered to belong to the Śaiva Siddhānta canon at the time when it was first composed: the hymns themselves appear to make no such claim for themselves.
The bhakti movement, which both parallels and was an influence upon northern Vaishnava bhakti, asserted a positive and devotional quality missing in Buddhist and Jain asceticism, yet still inherited from those religions a certain antinomianism, particularly a rebellion against caste and privilege.
In the twelfth century Aghorasiva, the head of a branch monastery of the Amardaka order in Chidambaram, took up the task of amalgamating Sanskrit and Tamil Siddhanta. Strongly refuting monist interpretations of Siddhanta, Aghorasiva brought a change in the understanding of Siva by reclassifying the first five principles, or tattvas (Nada, Bindu, Sadasiva, Isvara and Suddhavidya), into the category of pasa (bonds), stating they were effects of a cause and inherently unconscious substances, a departure from the traditional teaching in which these five were part of the divine nature of God.
Aghorasiva was successful in preserving the Sanskrit rituals of the ancient Āgamic tradition. To this day, Aghorasiva’s Siddhanta philosophy is followed by almost all of the hereditary temple priests (Sivacharya), and his texts on the Āgamas have become the standard puja manuals. His Kriyakramadyotika is a vast work covering nearly all aspects of Shaiva Siddhanta ritual, including the daily worship of Siva, occasional rituals, initiation rites, funerary rites, and festivals.
In Tamil Shaiva Siddhanta, the thirteenth century Meykandar, Arulnandi Sivacharya, and Umapati Sivacharya further spread Tamil Shaiva Siddhanta. Meykandar's twelve-verse Śivajñānabodham and subsequent works by other writers, all supposedly of the thirteenth and fourteenth centuries, laid the foundation of the Meykandar Sampradaya (lineage), which propounds a pluralistic realism wherein God, souls and world are coexistent and without beginning. Siva is an efficient but not material cause. They view the soul’s merging in Siva as salt in water, an eternal oneness that is also twoness.
Shaiva Siddhanta today 
Shaiva Siddhanta today is practiced widely among the Hindus of southern India and Sri Lanka. It is also prevalent among Hindus of the Tamil diaspora around the world.
Prominent Siddhanta societies, temples and monasteries also exist in a number of other countries. The United States island of Kauai, a part of Hawaii, is home to the Saiva Siddhanta Church, an organization that promotes the union of worldwide Hindus, Shaivites and others, through a publication called Hinduism Today. This was founded by Satguru Sivaya Subramuniyaswami (1927–2001), which is currently under the auspices of Subramuniyaswami's designated successor, Satguru Bodhinatha Veylanswami (1942- ).
Early theology 
Siddhas such as Sadyojyoti (ca seventh century) are credited with the systematization of the Siddhanta theology in Sanskrit. Sadyojyoti, initiated by the guru Ugrajyoti, propounded the Siddhanta philosophical views as found in the Rauravatantra and Svāyambhuvasūtrasaṅgraha. He may or may not have been from Kashmir, but the next thinkers whose works survive were those of a Kashmirian lineage active in the tenth century: Rāmakaṇṭha I, Vidyākaṇṭha I, Śrīkaṇṭha, Nārāyaṇakaṇṭha, Rāmakaṇṭha II, Vidyākaṇṭha II. Treatises by the last four of these survive. King Bhoja of Gujarat (ca 1018) condensed the massive body of Siddhanta scriptural texts into one concise metaphysical treatise called the Tattvaprakāśa.
Later theology 
The culmination of a long period of systematisation of its theology appears to have taken place in Kashmir in the tenth century, the exegetical works of the Kashmirian authors Bhatta Narayanakantha and Bhatta Ramakantha being the most sophisticated expressions of this school of thought. Their works were quoted and emulated in the works of twelfth-century South Indian authors, such as Aghorasiva and Trilocanasiva. The theology they expound is based on a canon of Tantric scriptures called Siddhantatantras or Shaiva Agamas. This canon is traditionally held to contain twenty-eight scriptures, but the lists vary, and several doctrinally significant scriptures, such as the Mrgendra, are not listed. In the systematisation of the ritual of the Shaiva Siddhanta, the Kashmirian thinkers appear to have exercised less influence: the treatise that had the greatest impact on Shaiva ritual, and indeed on ritual outside the Shaiva sectarian domain, for we find traces of it in such works as the Agnipurana, is a ritual manual composed in North India in the late eleventh century by a certain Somasambhu.
Monastic orders 
Three monastic orders were instrumental in Shaiva Siddhanta’s diffusion through India; the Amardaka order, identified with one of Shaivism’s holiest cities, Ujjain, the Mattamayura order, in the capital of the Chalukya dynasty near the Karnataka, and the Madhumateya order of Central India. Each developed numerous sub-orders. (see Nandinatha Sampradaya) Siddhanta monastics used the influence of royal patrons to propagate the teachings in neighboring kingdoms, particularly in South India. From Mattamayura, they established monasteries in regions now in Maharashtra, Karnataka, Andhra and Kerala.
- Xavier Irudayaraj,"Saiva Siddanta," in the St. Thomas Christian Encyclopaedia of India, Ed. George Menachery, Vol.III, 2010, pp.10 ff.
- Xavier Irudayaraj, "Self Understanding of Saiva Siddanta Scriptures" in the St. Thomas Christian Encyclopaedia of India, Ed. George Menachery, Vol.III, 2010, pp.14 ff.
- Flood, Gavin. D. 2006. The Tantric Body. P.120
- Flood, Gavin. D. 2006. The Tantric Body. P.122
- Flood, Gavin. D. 2006. The Tantric Body. P.34
- Flood, Gavin. D. 1996. An Introduction to Hinduism. P.168
- S. Arulsamy, Saivism - A Perspective of Grace, Sterling Publishers Private Limited, New Delhi, 1987, pp.1
- See, for instance, Dominic Goodall and Harunaga Isaacson, « Workshop on the Niśvāsatattvasaṃhitā : the Earliest Surviving Saiva Tantra? », in the Newsletter of the Nepal-German Manuscript Cataloguing Project No.3 (2007), p.4–6.
- See Alexis Sanderson's The Lākulas: New evidence of a system intermediate between Pāñcārthika Pāśupatism and Āgamic Śaivism. Ramalinga Reddy Memorial Lectures, 1997. In: The Indian Philosophical Annual 24 (2006), pp.143-217.
- Dominic Goodall, The Parākhyatantra. A Scripture of the Śaiva Siddhānta, Pondicherry, French Institute of Pondicherry and Ecole française d'Extrême-Orient, 2004, pp.xxix-xxxiv.
- Gavin Flood, An Introduction to Hinduism, Cambridge UP, 1996, chapter seven.
- See Alexis Sanderson, “The Date of Sadyojyotis and Brhaspati.” In Cracow Indological Studies 8 (2006), pp.39–91. (Actual publication date 2007.)
- Alexis Sanderson, The Saiva Exegesis of Kashmir, pp.242-248 (in Tantric Studies in Memory of Hélène Brunner, edited by Dominic Goodall and André Padoux, Pondicherry, French Institute of Pondicherry and Ecole francaise d'Extreme-Orient, 2007.
- Dominic Goodall, Problems of Name and Lineage: Relationships between South Indian Authors of the Shaiva Siddhanta, Journal of the Royal Asiatic Society, Series 3, 10.2 (2000).
- Extant lists are presented by Dominic Goodall in Appendix III of Bhatta Ramakantha's Commentary on the Kiranatantra, Pondicherry, French Institute of Pondicherry and Ecole francaise d'Extreme-Orient, 1998, pp.402-417.
- This is one of the few demonstrably pre-tenth-century scriptures of the Shaiva Siddhanta to have been completely translated into a European language: Michel Hulin, Mrgendragama. Sections de la doctrine et du yoga, Pondicherry, French Institute of Pondicherry, 1980, and Hélène Brunner-Lachaux, Mrgendragama. Section des rites et sections du comportement, Pondicherry, French Institute of Pondicherry, 1985.
- This manual, called the Kriyakandakramavali or Somasambhupaddhati, has been edited, translated and richly annotated by Hélène Brunner and published in 4 volumes from the French Institute of Pondicherry in 1963, 1968, 1977 and 1998.
- Flood, Gavin (2005). The Tantric Body: The Secret Tradition of Hindu Religion. I. B. Tauris. ISBN 1845110110.
- Siddha Saivism - Philosophy and Practices
- K. Ganesalingam, Notes on Saiva Siddhanta Philosophy
- Oxford Bibliographies, Saiva Siddhanta
- ŚANKARA - SIVAISM IN SOUTHERN INDIA - KASHMIR - LINGÂYATS