The religion of the ancient Tamils closely followed the roots of nature worship and some claim it close to its contemporary in North India, Vedic Hinduism. Tolkappiyam, one of the oldest grammar work in Tamil mentions Kottravai (Mother goddess) Sevvael (Murugan), Thirumaal, Vendhan (Indra) and Varunan .Other ancient works refer to Mayon (Krishna) and Balarama. The influence of Hinduism in Tamil literature rose again during the Bhakti period which documented the people organizing into Saivam(Shiva) and vainavam(Vishnu). 
The most popular deity was Murugan, who has from a very early date been identified with Karthikeya, the son of Siva. Muruga might have been a different deity originally stemming from a local deity. According to the noted expert on Tamil culture Kamil V. Zvelebil, "Subrahmanya-Murugan is one of the most complicated and baffling deities for analysis". The later(medieval to present) worship of Amman or Mariamman, thought to have been derived from Kotravai, an ancient mother goddess, also was very common. Kannagi, the heroine of the "Cilappatikaram", was worshipped as Pathini by many Tamils, particularly in Sri Lanka. There were also many temples and devotees of Thirumaal, Siva, Ganapathi, and the other common Hindu deities.

In the ancient Sangam literature, the Tamil landscape was classified into five categories, "thinais", based on the mood, season and the land. Each of these "thinai" had an associated deity such as "Mayavan", "Velavan", etc.

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