Cardiff, UK - Religious and faith organisations contribute more than £100m in economic benefits to Wales, a report says.
But the groups have little in return, with barely a quarter of faith communities getting public funding, the research found.
According to the study, around 40,000 unpaid volunteers do 80,000 hours of community work a week
And it discovered faith communities maintain more than 1,600 listed buildings with 2.5m visitors annually.
Gweini, the Council of the Christian Voluntary Sector in Wales, conducted the survey with the Wales Council for Voluntary Action (WCVA).
It is thought to be the first time the contribution of religious organisations has been calculated in this way.
Called Faith in Wales: Counting Communities, it looked at congregations ranging from long-established Christian churches to Hindu and Muslim groups as well as Baha'i, Buddhist, Jewish and Sikh communities.
The research found that in addition to the volunteers, the groups had 1,400 paid staff working 23,000 hours a week.
It found their unpaid contributions to Welsh society ranged from job training and bereavement counselling to choirs and football clubs.
The survey found faith groups contribute to the Welsh language with a third of churches in Wales holding services in Welsh and 800 holding some kind of Welsh language-based activity.
The study also concluded faith groups provide accommodation for local organisations - more than 600 have their own purpose-built community centres while 800 rent out rooms at a nominal charge - and play an important part in music and sport.
Faith communities were largely self-financing, the report said, with only 27% having funding from public sources.
Based on population, the groups' contribution would mean that religious organisations across Britain generate at least £2.1bn annually.
The report concluded: "All the major faiths have an ethos of encouraging their members to serve civil society as individuals, for example, through their businesses, their jobs, their families and as neighbours.
'Valuable role'
"Many important voluntary organisations are inspired by the ethos of one or other faith."
The Archbishop of Canterbury, Dr Rowan Williams, welcomed the report and said he hoped it would be widely read throughout the UK.
Dr Williams said: "Counting Communities demonstrates just what an extensive and valuable role faith communities play in today's society.
"The contribution made by Christians and people of other faiths to public life in Wales that is revealed in this report, offers both example and encouragement to us all.
"I hope that the report is widely read, not only in Wales, but also in all parts of the United Kingdom."