More than 5,500 churches across the UK, including several famous cathedrals, have converted to renewable power to help combat climate change.
The Church of England warned the issue was "one of the great moral challenges of our time".
It said thousands of Christian and non-Anglican places of worship were now using 100% renewable electricity.
Salisbury, Southwark, Liverpool and St Albans cathedrals are among 15 to have signed up to green electricity tariffs.
With an average annual church electricity bill of around £1,000, it is estimated British churches have diverted more than £5m from fossil fuels to clean energy providers.
The number of cathedrals running on 100% renewable electricity has been boosted by the Church of England's procurement initiative Parish Buying changing its bulk energy purchase to 100% renewables.
Other churches have made the move through the Big Church Switch campaign run by Christian charities Christian Aid and Tearfund and the Church of England's Environment Programme.
Bishop of Salisbury Nicholas Holtam, the Church of England's lead bishop on the environment, described climate change as "an enormous injustice" which "hurts the poor first and worst".
"It's fantastic to see churches doing their bit to ensure they reduce their impact on the environment. They are also giving a boost to clean energy, which is essential to reduce harmful carbon emissions," he said.
"Switching to responsible sources of electricity may seem like a small thing on its own, but when joined together it can make a real difference."
Former Archbishop of Canterbury and chairman of Christian Aid, Dr Rowan Williams, urged the government to set a target to cut UK emissions to zero overall by 2050 to ensure Britain "remains a green and pleasant land at home and a climate leader abroad".