Oldest snake temple - Mannarasala temple, Kerala

Mannarasala Snake Temple,Kerala. Alamy

Haripad is a town in Alappuzha District, Kerala, S. India located between Alappuzha and Kollam towns. It is close to the Arabian Sea and connects Mavelikkara and Thrikkunnappuzha towns. It is the land of "Mayura Sandesa," the land of fascinating snake boats, and of music, dance and drama native to this area.

Mannarasala Snake Temple,Kerala. FindMessages.com

Snake worship  transcends religions and countries and has been in existence  since ancient times and is still prevalent among Hindus and Christians.  In Christianity too  St. Mark is associated with snakes. “Some Christian churches '' are known to use venomous snakes as part of their worship drawing  inspiration from the gospel of Mark 16:18. Ancient Israelis and Egyptians, Africans, Cambodians,  Mesopotamians and Nordic communities have religious belief related to snakes.

There is a plethora of tales of Serpent gods  and goddesses  found in the  Hindu mythology. In the Hindu pantheon there are Naga gods and goddesses. Nagpanchami in many parts of  India and Ayilayam pooja in Kerala are important festivals that attract a large number of devotees. The strong belief, that snakes represent  good spell of rain, fertility and prosperity, is common across the  length and breadth of India.

Among the 48 Hindu temples there and  in the fringe areas surrounding the countryside,  two most famous temples are Subrahmanya Swamy temple and Mannarasala Temple; the former dedicated to Lord Subramanya, is one of the oldest temples in Kerala and was severely damaged but for  Koothambalam and gold flag mast in 1096 AD. The temple was rebuilt  during the time of  King Chithira Thirunal Balarama Varma (1930-1949 ); the latter is a Nagaraja temple located near Haripad in the midst of a forest area doted with  thousands of  stone carved snake images all along the paths and in the tree shades. There are more than 30,000 stone-carved snake images. Perhaps, the largest temple in terms of stone idols installed dedicated to serpents in the world. It is also an ancient temple and a major center of pilgrimage for the devotees of serpent God Nagaraja (also Nagarajan). It is believed to have been established by Lord Parasurama.  Sarpa Yakshi and Naga Yakshi are the beloved consorts of Nagaraja. Here  Nagaraja - main  deity is endowed with the form of Hari (Lord Vishnu) and the spirit of Lord Shiva.

Mannarasala Snake Temple,Kerala. The Bold Indian

Childless couples  from all over Kerala and other states and sometimes overseas  come over here reposing deep faith in the presiding deity's power  to grant a child. To propitiate the God and to seek His blessings and fertility, they undertake the initial pilgrimage to this temple. Once their prayer is granted and are blessed with a baby, they come back here - a sort of thanksgiving pilgrimage with the baby and a stone image of a snake to be installed at the temple as a mark of gratitude, and besides, they do special pooja (prayer) and conduct thanksgiving ceremonies.
Unlike other temples of  Kerala or else where, the beliefs and rituals associated with the Mannarasala temple are different  and this is the only temple where the puja protocol  is headed by a Brahman woman. Coming from a hereditary family, enjoying rights to conduct temple pooja, the woman assumes the role of a mother. Legend has it that the first priestess gave birth to a five-headed Naga which is believed to safeguard the family. Living as a Brahmacharini (practices  strict celibacy) and observing long hours of meditation, prayer and fasting as a priest, she blesses the people for good health, prosperity and longevity. The  woman head priest observes: ''Those who worship me with faith and devotion will have have every thing and be free from diseases.'' The woman priests who come from that family are said to have some kind of mystical power.

Mannarasala Aayilyam is the major festival here celebrated in the month of Kanni and Thulam (September - October). As part of the festival, all snake stone images on the temple premises and in the groves are taken in procession to the illam (Veedu in Tamil) of the priest family that is associated with the temple. Offerings - rice-flour and milk (Nurum palum), cooked rice and red fluid (Kuruthi) made by mixing lime and lemon are offered. The important feature of this traditional procession is the female priest herself will carry the idol of Nagaraja with devotion and the entire oorvalam (procession) is conducted with  intense passion and commitment.  
Ref:
https://en.wikipedia.org/wiki/Mannarasala_Temple