The lecturer, T J Joseph, was dragged out of his car and hacked with sharp weapons by the assailants while he was returning from a church along with his family, including his sister and mother. His right palm was severed while he suffered cut injuries in his left leg, they said.
52-year-old Joseph was rushed to a private hospital where he underwent a surgery, hospital sources said.
A Malayalam lecturer at Newman College in Thodupuzha in Idukki district, Kerala, Joseph was arrested in April last after the question paper which he had set for the B.Com II year internal exams sparked protests by Muslim outfits, which claimed a reference to Prophet Mohammed in it had hurt their religious sentiments.
He was later suspended from the college, whose authorities also apologised for the mistake.
Police said they were searching for the assailants, numbering around eight.
Meanwhile, CPI(M) state secretary Pinarayi Vijayan condemned the "Taliban model" attack on the lecturer and urged all Keralites to protest against the "heinous crime".
Vijayan said in a statement that everyone shared the view that the question paper prepared by the lecturer had hurt the religious sentiments of Muslims. But such an attack on the lecturer by "extremists" should not happen in a civilised society, he said.
Vijayan said communal elements who wanted to create a rift in society was behind the attack. Vijayan wanted the government to swiftly act and bring the culprits to book.