"I hear that about 200 environmental groups have joined together in opposition to the president's proposals," Wesley Granberg-Michaelson told a conference in Washington, DC, at the end of May.

"What is the church's role? Simply to join that lobbying chorus as group 201? Or is there something unique and true we bring to this debate, precisely because we are churches?"

The environmental justice ministries conference took place just after the Bush administration released its energy policy.

Critics say that the Bush plan makes some gestures towards conservation, but would expand US reliance on oil, coal and nuclear energy, "which destroys land, pollutes air, and harms public health". It would fail to develop a clean, safe and efficient energy system, or to reflect biblical standards of justice and sustainability.

"US energy use is causing global warming," said Robert Edgar, general secretary of the National Council of Churches. "And the president's plan is only going to make the planet hotter."

In his keynote address, Wesley Granberg-Michaelson, general secretary of the Reformed Church in America, told the conference that scripture gave four foundations for care for the environment.

The first is God's covenant with the earth and all living things. "Creation is chosen by God before God chooses and calls a people," he said. Second, the idea of "nature" as a separate object to be used, exploited and subdued - which is the hallmark of the industrial age - results from the break in relationship between God, humanity and the creation.

Thirdly, Christ came to reconcile and hold together all things, to restore a creation "groaning and looking towards its redemption". Finally, Granberg-Michaelson concluded, "creation becomes a gift of grace, a gift to be offered back to God for the sake of the life of the world."

Ada Maria Isasi-Diaz, professor of Christian ethics and theology at Drew University, echoed this emphasis on mindset. "We need a radically different understanding of being in the world," she said. "Otherwise the same assumptions about it being there for us to use without limits will keep coming back."

Participants took time out from the conference for an interfaith rally on Capitol Hill. They visited their senators and representatives, presenting each with an energy-efficient compact fluorescent bulb. And they formed a human "bar graph" to illustrate the shaming statistic that the USA, with less than 5% of the world's population, contributes more than 22% to greenhouse gas emissions.

One of Mr Bush's first foreign-policy achievements was the failure of the US-European Union summit to reach any agreement on the Kyoto protocol. Before setting out for Europe in June, the president already made it clear that the US would not sign up to reduce carbon dioxide emissions by 5.2% from 1990 levels by 2012 - a target, environmentalists say, that falls far short of what is really needed.

Granberg-Michaelson joined with 38 other religious leaders in addressing an open letter to "the president, the congress and the American people" on energy conservation and God's creation. Other signatories included Clifton Kirkpatrick of the Presbyterian Church (USA), John Thomas of the United Church of Christ, Richard Hamm of the Disciples of Christ, and George Anderson of the Evangelical Lutheran Church in America.

The letter insists that the "perspectives of faith and values" must shape the US energy discussion. At stake is "the future of God's creation on earth; the nature and durability of our economy; our public health and public lands; the environment and quality of life we bequeath our children and grandchildren. We are being called to consider national purpose, not just policy."

The letter makes five bullet points:

Energy conservation is faithful stewardship.
Energy conservation is intergenerational responsibility.
Energy conservation is justice for all peoples and nations.
Energy conservation is prudent human action.
Energy conservation is global leadership and solidarity.

Conservation, it says, is "a personal and a public virtue - a comprehensive moral value".

"Everything we do to assure safe and sustainable energy domestically must at the same time promote it internationally. We must join in binding international agreements, such as the Kyoto protocol, which set energy conservation targets and timetables. Preventing climate change is a pre-eminent expression of faithfulness to our creator God."