Dr Abby Day from the University of London spent several months with older women in churches in England, Scotland, the US, Canada and Sri Lanka for her study, called Powers and Pieties.
She found that in most congregations older women made up more than half of the total number of people, and also contributed vital but uncelebrated acts of service such as cleaning, making and serving food and drink, tidying, washing and organising events such as bring-and-buy sales.
Mrs Day concluded that the Church would be considerably weakened when these older women, born in the Twenties and Thirties, pass away.
Speaking to the Sunday Telegraph, she said: "Their often invisible labour ensures the church's continuity and enriches surrounding communities.
"Generation A is irreplaceable and unique.
"When this generation finally disappears within the next five to 10 years, its knowledge, insights and experiences will be lost forever."
Sally Barnes, from the organisation Women and the Church, told Premier's News Hour: "I think they make an absolutely invaluable contribution in very many ways.
"I think the Church would find it very hard at the moment to survive without them and all they contribute, and have contributed.
"Women, particularly older women, do a huge amount of contributing in terms of cakes and flowers and things like that, but underneath all that there's an awful lot of underused, undervalued gifts that they could bring.
"The church is going to have to change and adapt. Middle-aged women, young women, they're often all in professions.
"Lay women are sometimes disregarded. Their views, their real views, are disregarded, so they don't like to express them... not being asked, not being valued, when they offered their ideas and thoughts and gifts outside what you might call the norm."
Listen to Premier's Hannah Tooley speaking to Sally Barnes on the News Hour here:
