The 127 Hours star, whose mother is Jewish, has always expressed interest in taking part in the faith's traditional coming-of-age celebration and his pal Seth Rogen has organised a special bar mitzvah for charity later this month (Oct15).

However, Seth reveals James was actually welcomed into Judaism during a private ceremony on Friday (02Oct15), when he donned a tallis prayer shawl and kippah and read from the Torah in Hebrew.

"He did his actual bar mitzvah last night," Seth told at the New York Film Festival on Saturday (03Oct15). "The Rabbi wouldn't do it on the actual event, so he did it last night at our friend's house and we filmed it and we'll show it at our fundraiser. He really got bar mitzvahed (sic)!"

The charity party is set to be hosted by Seth to benefit his Hilarity for Charity organisation, which aims to raise money for Alzheimer's research, and the Knocked Up funnyman reveals he wants to recruit Jewish pop stars to set up a traditional hora dance performance.

"I'm trying to organise a hora, specifically with some Jewish pop singers," Seth confessed. "If there's any singer who's Jewish, we're getting them in there. Lisa Loeb. I think Haim is Jewish, I'm not sure. But yeah, we'll find them."

Miley Cyrus will also be among the performers at James' bar mitzvah party, which will take place at the Hollywood Palladium on 17 October (15).

Seth launched Hilarity for Charity in 2011 with his wife Lauren Miller after her mother was diagnosed with Alzheimer's.