Climate change campaigners have long liked to believe they are acting on the side of the angels. Now it seems the angels may be acting on the side of the climate change campaigners.

The growing involvement of the world’s religious organisations in the fight to tame global warming, which will hit the poorest hardest, took a significant step forward on Friday when the Church of England for the first time decided that climate change was an ethical reason to dump some investments from its £9bn endowment.

Earlier in the week, the Vatican called for a moral awakening on climate change, ahead of an encyclical from the pope, which is expected to be one of the most influential interventions in a year that ends with a crunch UN climate summit in Paris. With Methodists, Quakers, United Reformed Presbyterians and many other denominations across the UK and the world taking action on climate change by selling off their investments in coal, oil and gas, the question is how great an impact will the moral authority conferred by religious groups have?

“In all the great social movements in history, a part of the church has always been at the forefront, such as Archbishop Desmond Tutu with apartheid, Baptist minister Martin Luther King with civil rights in the US, and William Wilberforce with slavery,” argues Christine Allen, Christian Aid’s director of policy and public affairs. “But there has always been a bit of the church at the back too – the church is broad. It takes a while to get to agreement, but when that happens things move very fast. We really are at that tipping point now.”

Tutu, revered for his role in helping to defeat apartheid in South Africa, has already given his whole-hearted backing to fossil fuel divestment. “People of conscience need to break their ties with corporations financing the injustice of climate change,” he told the Guardian in 2014. The movement is growing rapidly, with more than 200 organisations already having divested, including cities, universities, charitable foundations and the Guardian Media Group, after the Guardian’s Keep it in the Ground campaign asked the Gates Foundation and Wellcome Trust medical charities to divest from fossil fuels. Oxford University is among many institutions set to make a decision in the coming months.

A series of analyses have shown that the world’s existing reserves of fossil fuels are several times greater than can be burned while keeping the temperature below the 2C safety limit agreed by the world’s governments. So proponents of divestment say it is wrong to invest in fossil fuel companies that still spend many billions a year looking for more coal, oil and gas. Furthermore, authorities such as the World Bank and Bank of England have warned that fossil fuel reserves will be left worthless if the action needed to cut carbon emissions kicks in.

Bill McKibben, an environmentalist and divestment campaigner, says: “The financial case for action is clear but churches are, or should be, specialists in identifying that other kind of risk, where human beings don’t pay enough attention to the poorest and most vulnerable among us. When the Church of England acts, or the pope speaks, it’s a potent reminder.”

Ben Caldecott, director of the Stranded Assets programme at Oxford University, notes that the aim of the divestment campaigners is to bankrupt fossil fuel companies morally, not financially, and that religious groups have a special significance in creating this stigma.

“Faith groups remain influential in shaping societal norms and views of particular industries,” he says. “But even if this impact is limited in increasingly secular societies, it still provides succour to those within non-faith groups pushing for divestment. Either way, I think it increases the reputational risk for fossil fuel companies.”

The financial argument for divestment appeals particularly to investors with long-term objectives, meaning faith groups are playing a significant role, says Mark Campanale, founder of the Carbon Tracker Initiative, which pioneered the financial analysis of the carbon bubble. “You could not get a group more long-term in their outlook – they have been around for millennia,” he says. Another feature of religious groups is their international reach, potentially helping to bridge the differences between nations that have dogged climate change negotiations to date. “Faith groups are transnational tribes and can bring different political forces together,” says Allen.

There are many religious organisations with significant endowments now expressing anxiety about fossil fuel investments to their fund managers, which is making ripples in the fund management world, Campanale says.

“The fund managers are having to work out what to do and dig into the risks. One of the fundamental rules of investment management is you cannot ignore your clients, and when you get a significant client [like the Church of England] come along and express concern, you have to sit up and take notice, or when your three-year contract is up, you’ll be gone.”

However, a frequent counter-argument to divestment is that it is better to remain invested and engage with a fossil fuel company to change its behaviour, and the Church of England’s divestment was not complete. It sold off £12m of highly polluting coal and tar sands investments, but retains about £100m in, for example, Shell. That has disappointed campaigners, who point out that part of Shell’s operations are in tar sands and exploiting the Arctic, both deemed incompatible with tackling climate change by scientists. Its new benchmark of accepting companies that derive less than 10% of revenue from thermal coal (used for generating electricity) still allows it to invest in firms with some of the largest coal reserves on the planet.

Some observers among the faithful raise questions about the Archbishop of Canterbury, Justin Welby, who had a career in the oil industry before becoming a priest. “There is a sense of disappointment that Welby has not spoken out more,” said one, requesting anonymity. “But the pope and the Paris summit have forced his hand and he’s expected to speak publicly on this issue in the autumn.”

The Rev Canon Giles Goddard, who is campaigning for full divestment from the Church of England, said this week’s steps were a symbolic beginning. He wants the church to use its influence in the wider world: “People do look to the Church of England for leadership on ethical investment, which is why we got into so much trouble over [our investments in pay-day lender] Wonga.”

Cardinal Peter Turkson, who drafted the forthcoming papal encyclical, drew on the Bible for his message this week: “The lesson from the Garden of Eden still rings true today: pride, hubris, self-centredness are always perilous, indeed destructive. The very [fossil fuel] technology that has brought great reward is now poised to bring great ruin.”