Tamil Sidhha movement were more oriented toward journey of knowledge, who believed only through knowledge one can realize the god, as against the popular form of Hinduism the Bakthi movement. Tamil Sitthar's literary movement started with Thirumoolar. The later Siddhas especially Civavakkiyar was very critical against mainstream Hinduism.  He criticized idol worship and people running after temples. His philosophy was God is in you realize him.  You will see more of Civvakkiyar in the next few weeks.