As an assistant working for Peter Percival – a Methodist Christian missionary, he helped translate the King James Bible into the Tamil language.

He also attempted to reform Hindu Shaivism and customary practices in Sri Lanka,[6] such as by showing Shaiva Agamas (scriptures) prohibit animal sacrifice and violence of any form.

At the time of Navalar's birth, they were a part of the socio-political leadership in Jaffna peninsula, a strip of land (40 by 15 miles) separated from South India by the Palk Strait.

The principal town Jaffna and the peninsula (as well as the West Coast and Eastern regions of Sri Lanka) were predominantly Tamil Saiva in culture distinct from that of the Sinhalese Buddhists elsewhere.

Arumugam Navalar felt that Hindu Saivites needed a clearer understanding of their own ancient literature and religion.

[21] The 18th and 19th century Tamils in India and Sri Lanka found themselves in the midst of intrusive Christian missionary activity and their polemics against Hinduism.

According to D. Dennis Hudson, Tamil Saivas opposed Christian missions from the earliest days, based on indirect literary evidence.

Printing press was not available to the Hindus in colonial era South Asia, and the Shaiva community used their oral tradition and handwritten notes for anti-missionary literature.

Arumuga Navalar was one of the first Tamils who became adept at this information war, and to undertake as his life's career the intellectual and institutional response of Saivism to Christianity in Sri Lanka and India.

While Arumugam Navalar was still working under Peter Percival and translating the Bible, he published a seminal letter in The Morning Star under a pseudonym in September 1841.

If Christians find their churches, rites and symbols as pedagogically useful, why shouldn't Shaiva Hindus have the same human rights and religious choices, argued Navalar.

[24][25][26] His letter admonished the missionaries for misrepresenting their own religion and concluded that in effect there was no difference between Christianity and Hindu Saivism as far as idol worship and temple rituals were concerned.

The sermon topics were mostly ethical, liturgical, and theological and included the evils of adultery, drunkenness, the value of non-killing, the conduct of women, the worship of the linga, the four initiations, the importance of giving alms, of protecting cows, and the unity of God.

The school did not follow the traditional Tamil teaching system, in which each student worked on his own pace and the teacher pupil ratio was extremely low.

After listening to his preaching and understanding his unusual mastery of the knowledge of Agamas, the head of the monastery conferred on him the title Navalar (learned).

[30] While in India he published two texts, one was an educational tool (teachers guide) Cüdãmani Nikantu, a sixteenth-century lexicon of simple verses and Soundarya Lahari, a Sanskrit poem in praise of the Primeval Mother Goddess Parvati, geared towards devotion.

[32] Other notable texts published included The Prohibition of Killing, Manual of worship of Shiva temple and The Essence of the Saiva Religion.

His first major literary publication appeared in 1851, the 272-page prose version of Sekkilar's Periya Puranam, a retelling of the 12th-century hagiography of the Nayanars or Saivite saints.

[34] A Methodist missionary, who had worked in Jaffna, described the manual thirteen years after it had appeared as: "Displaying an intimate and astonishing acquaintance with the Holy Bible.

(the author) labors cleverly to show that the opinions and ceremonies of Jehovah's ancient people closely resembled those of Shaivism, and were neither more nor less Divine in their origin and profitable in their entertainment and pursuit.

The notion of merit held by the Hindus, their practices of penance, pilgrimage, and lingam-worship, their ablutions, invocations, and other observances and rites, are cunningly defended on the authority of our sacred writings!

That a great effect was thus produced in favour of Sivaism and against Christianity cannot be denied".This manual was widely used in Sri Lanka and India; it was reprinted at least twice in the 19th century, and eight times by 1956.

[34] According to D. Dennis Hudson – a World Religions scholar,[36] Navalar's legacy began in Jaffna, but spread more broadly to Sri Lanka as well as Southern India.

[37] He produced approximately ninety-seven Tamil publications, twenty-three were his own creations, eleven were commentaries, and forty were his editions of those works of grammar, literature, liturgy, and theology that were not previously available in print.

[29] His reforms and contributions were added to by scholars such as V. Kalyanasundaram (1883–1953), and Maraimalai Adigal (1876–1950), who developed their own schools of theology within the Hindu Saiva heritage.

[29] Although it is difficult to quantify as to how many Hindus may have converted to Protestant Christianity without his intervention but according to Bishop Sabapathy Kulendran, the low rate of conversion compared to the initial promise was due to Navalar's activities.

Although he never cared much for his caste identity, as he considered all living beings as equal, his efforts led to the consolidation of traditional privileges of Hindu Saiva Vellala (farmers, landlords) and Karaiyar (warriors).

[39] Navalar's insistence on the Agamas as the criteria of Hindu Saiva worship, moreover, gave momentum to the tendency among Tamils everywhere to attempt to subsume local deities under the Agamic pantheon and to abandon animal sacrifice altogether.

Arumuga Navalar found support from the Brahmins and his own literati caste of Vellalas in the Tamil community, according to Wilson, because he accepted and recognized their caste-based status.

Navalar, states Schalk, was a theologian who used indirect "metonymic language" with "coded words" that metaphorically supported the traditional caste system privileges within the colonial era administration.