The percentage is broken down as Hindu 81.3%, Muslim 12%, Christian 2.3%, Sikh 1.9%, Judaism 1.0%, other groups including Buddhist, Jain, Parsi at 2.5% (2000).
In terms of languages spoken there, English enjoys mainstream status and is the most important language for national, political, and commercial communication. Hindi is the national language.
Actually one of the women I work with was at the Stock Exchange back in '92 (I think) when it was bombed (along with the Air-India, and other stuff).
She was pretty traumatized and suffered almost a post-tramatic shock type after the WTC attack.
I wouldn't be surprised that the "feelings" she carries for Muslim seperatists makes her perceive them more. She say's Muslims have a very big presence in India, especially Fridays.