At 38, his parents were likely born post separation, or immediately pre-separation. If they were Muslim, they'd probably be Pakistanis or Bangladeshi, although there are still substantial numbers of Muslims in post separation India.
He's most likely Hindu, with no love lost for Muslims. He could be Christian too. I worked with a very bright young lady whose parents were Christians from Southern India. She'd be close to his age, probably a little younger.
There are approximately 174 million Muslims in India (according to government census 2001), i.e 16.4% of the population. India has the second largest population of Muslims in the world (the largest being Indonesia).
See http://en.wikipedia.org/wiki/Islam_in_India