St Thomas had many believers of Jesus in Thamizhagam (which was the southern portion of the Indian peninsula). They believed in the doctrine of a perfected sacrifice that the Saviour of the world had offered by shedding blood and dying on the cross. Temples were constructed in Indian style as places of Christian gathering, a couple of which still stand a witness to this fact in the Malabar coast. The Christian believers were called Mar Thoma Christians.

The concept of a Creator God that Thomas brought to India was new to the inhabitants. (India was not one united country then. It had several smaller kings (fifty-six according to one estimate) each ruling over a small region). Also, the doctrine of one final sacrifice of Jesus Christ putting an end to all religious sacrifices was new to them. Receiving God’s favour just by believing in His word and His Son started quickly winning believers to Christ. Thomas had managed to reach a vast majority of the Thamizhar of the then Thamizhagam composed of Tamil Nadu, Kerala and a portion of Karnataka and Andhra of today. One estimate puts the number of such believers to 3.3 million.