The Alliance of Religions and Conservation and the World Wildlife Fund brought together 11 major faiths-representing some 4 billion people-to ask that very question. Here are some "Sacred Gifts for a Living Planet" that they came up with.
Catholic Benedictine Sisters will double environmental education programs in their schools.
American Jews will cut energy use by 10 percent in religious buildings.
Muslim fishermen in Zanzibar pledge to protect turtle nesting sites.
7,000 Nepalese Sherpas will reintroduce sustainable Buddhist forest management on Mt. Everest.
40 millions Taoists won't use endangered species in traditional medicine.
Japan's Shintos to buy only sustainably grown wood for shrines.
Hindus in Orissa, India, will restore the state's sacred forests.
Orthodox Christians promise to clean up the Danube.