For Abdul Hakim, who has always heard his son call him abba jaan, the word came as a shock.

His son Hafesuddin (22), one of the missing men from Kerala and now suspected to be a part of ISIS network, called Hakim a 'kafir' - a person who rejects or disbelieves in God.

"My own son called me a kafir. Radicalism changed my son completely," said Hakim, trying to control his emotions as the love for his son was overwhelmed by anger at what he has done.

With the news of missing youths from Kerala hitting the headlines, Hakim is a worried man.

He wondered where he went wrong in raising Hafesuddin, that he one day texted him, "I am now get the jannat (heaven), here no tax, no Sharia law, nobody here catching me, very good place".

Speaking to CNN-News18, an anguished Hakim, said, "If he does not like India, if he acted against the country, I don't want to see him, even though he is my son.I don't even want to see his body."

Saying he has no clue how his son got radicalied, Hakim added. "I am an Indian, don't even wish to see my son's corpse ever."

On July 28, Hafesuddin left home to study the Quran in Calicut but two days later he said he was travelling to Sri Lanka for further studies.

A day before Eid, when his family members were waiting for him to return, they got a text message which read, "He is going to heaven with a cause."

"He didn't say anything about his location. He said that he wanted to teach the Quran," Hafesuddin's father said.

When asked did he notice any changes in Hafesuddin, he said, "Two years ago he started growing his beard. He told me that he want an Islamic state."

Hakim could never figure out what what overcame his son. "He does not like me anymore. I don't know why he doesn't like me anyomre, " he said.