The new show - which will be co-created by 'Avenue Q' writer Jeff Marx - is currently being developed by the comic duo but is yet to be given a title.
Marx told Bang Showbiz: "Trey and Matt were over with me in London recently while I open 'Q' here and so far we've written about four songs but we've got loads more ideas.
"The show is going to have nothing to do with their show, 'South Park', or my musical. It'll be something totally new and it's going to be something totally different.
He added: "It's going to be about Mormons and it's going to be really funny. we hope." The 'South Park' creators are no strangers to poking fun at organised religion.
They most recently attacked former cast member Isaac Hayes and his Scientology beliefs.
The star's character, Chef, was depicted as a paedophile and killed off after he quit the cult animated show complaining that Parker and Stone actively promoted intolerance and bigotry.
It is believed his outrage stemmed from an episode aired last year which mocked fellow Scientologist Tom Cruise.
'Avenue Q' - which has recently opened in London's West End - is an adult-themed musical inspired by a number of puppet based children's TV shows, including 'Sesame Street'.