The church in the name of St. Antreus is believed to have been made of wood in 1581. It was reconstructed with stone in 1597. The church in the name of St. Thomas is believed to havebeen destroyed in sea erosion and it was the Portuguese who installed the idol of Antreus instead of St. Thomas.
Arthunkal is the biggest pligrim center in Central Kerala that celebrates the Feast of St. Sebastian. St. Sebastian is believed to be one who protects people from small pox, chicken pox, cholera and such other diseases. During the Feast, the idol would be taken out in a procession to the sea shore and then taken back to the church. People crawl on their knees, and roll on the ground en route to the sea shore and also to the church, as an offering. Limbs of the body made in gold and silver are offered to the church.
Taking out the arrow in the procession, is also one of the main rituals. The festivities last for 7 days. The Feast on the eighth day is very significant. There are many idols at the old church, including that of St. Thomas and Holy Mary.