Secretive Christian community Gloria­vale has built up over $40 million in assets ­- including aircraft for its ­charter flight service - through a charity that pulls in millions every year.

Gloriavale's most recent ­balance sheet, registered with the Charities Services on ­January 31, states its Christian Church Community Trust has $41.4m in total assets. Most of that is in land ($10.4m) and buildings ($11.6m) but it also has deer and dairy stocks worth $4.8m and $928,000 in "vehicles and aircraft".

Gloriavale's accounts also show a healthy cashflow, with annual returns over the past seven years never seeing income drop below $3.9m.

The most recent return saw a $1m jump in revenue to $6m. A Gloria­vale spokesman declined to comment.

Gloria­vale, which will this week be the focus of a documentary looking at the roles of women in the ­community, has an emphasis on earning cash through industry and farming but the ­documents also show it is a beneficiary of tithing ­income, with $2.8m gifted from its followers.

Massey University Professor Peter Lineham is an expert in New Zealand's religious history and ­activity.

He says Gloriavale is one of a small group of churches ­doing well ­financially - but it's doing it ­differently to others.

Gloriavale is based on farmland in Haupiri on the West Coast of the South Island and Lineham says it "has done amazing things for a very poor part of the coast". Part of its success lies in its ­ability to hang on to the devoted, compared to high turnovers of followers seen in freer, inner-city churches.

But, he says, it is also a very ­regulated existence.

"It's a highly controlled life and manipulated structure with ­arranged marriages. It's the ­exact opposite of the free-wheeling commercially run operation that's trying to build its numbers," Lineham said.

"Their recruitment is ­entirely from a very high birth rate. But every single member in the ­community is in fact working under community orders, for the community. Nobody gets a ­separate income. All expenditure is controlled by the community."