Religious leftists view capitalism as the root of a rapacious greed that causes men to exploit and even destroy the natural environment in exchange for financial profit. To combat these forces, religious leftists commonly anoint themselves as stewards of God's earth, committed to defending its air, water, animals, plants, and natural resources from the ravages of free-market economies – especially America's.

According to Ron Sider, president of Evangelicals for Social Action:

“Christians must become vigorous environmentalists because God’s Word demands it, because we are destroying the Creator’s garden, and because many secular environmentalists are on a deep spiritual pilgrimage.... The way to defeat Satan is for all Christians to become committed environmentalists and to ground their struggles to save the earth on solid biblical foundations.... We need to repent of our unspoken belief that more is better, that more and more material abundance brings fulfillment.”

The Christian author Paul Brand warns, “We need to repent of our willing cooperation in our money-centered culture, which is depleting the natural resources that God designed for all humankind.”

Paul Gorman, founder of the National Religious Partnership for the Environment, says: “We don’t believe we are going to reverse the environmental crisis by simply passing laws.... Unless you have that fundamental change in values, many of us believe environmental degradation will be irreversible.”

Rev. Joan Brown Campbell, former General Secretary of the National Council of Churches, has proclaimed the virtues of the Kyoto Protocol which seeks to impose massive environmental restrictions and financial burdens on the United States while requiring virtually nothing of developing industrial nations like India and China. Campbell insists that an acceptance of the radical environmentalist movement's assertions about man-made global warming ought to be considered a “litmus test for the faith community.”

In 2004, Sojourners founder Jim Wallis asserted that “religion must talk about the environment as God's creation to protect and be good stewards of.” Three years later, Wallis expressed his great admiration for “environmental evangelist” Al Gore's crusade against global warming. Wrote Wallis: “There is more and more evidence that the ... polar ice caps are melting at a shocking rate.... It is indeed a crisis of biblical proportions.”

In 2006, the National Association of Evangelicals and the Center for Health and Global Environment met at Harvard Medical School for a retreat to unite faith leaders and scientists on issues of climate change and global warming. Participants drafted and signed a call-to-action, which they presented in 2007 to President George W. Bush, House Speaker Nancy Pelosi, congressional leaders, and national scientific and evangelical organizations.

Also in 2006, scores of evangelical leaders signed an Evangelical Climate Initiative pledging their efforts to combat global warming. Two years later , 46 leaders of the Southern Baptist Convention – America's largest Protestant denomination – signed a similar declaration.

In November 2009, religious leaders from around the world gathered in England, along with United Nations Secretary General Ban Ki Moon, to commit themselves to collaborative action against global warming, which they said was chiefly a result of human industrial activity and the greenhouse gases it emitted.

This section of Discover The Networks examines the environmentalist worldviews, objectives, and activities of many key figures who comprise the religious left.