Lord Shiva in the temple is a swayambumurthy.Dedicated to Shiva, Idumbavanam is believed to be the place where Yama, the god of death worshipped Shiva in order to rid himself of the sin of trespassing him and tried to take Markandeya to the netherworld.
Once, the gentle traits (Satva Guna) of Lord Brahma began to decline due to the curse of Lord Shiva. To regain the character loss, Brahma took on a pilgrimage to Shiva sthalas. Pleased with his efforts, Lord Shiva granted darshan in His wedding form with Mother Parvathi, Vinayaka and Muruga. Hence, Lord Shiva is praised as Sarguna Nathar – Lord of Gentle Characters. Lord Brahma created a spring – Brahma theertha and launched the festival, Brahmmotsava in Vaikasi-May-June.