As religious leaders and their congregations go green, they've neglected one Judeo-Christian teaching that could cut energy consumption and pollution by 14.2857 percent.
That's one-seventh, just as the Sabbath halts work one day out of the weekly seven.
The day of rest – long considered a gift from God – is meant to create a joyful, liberating respite from worldly concerns such as work and consumption, activities that both use the earth's resources.
So renewed observance of the Sabbath could also be a gift to the air, land, and water that we consume the other six days of the week.
"Six days you shall labor and do all your work," Yahweh told the Israelites at Sinai, "but the seventh is a sabbath of the Lord your God; you shall not do any work."
Jews have interpreted the Fourth Commandment to mean that they cease creative labor or work on the seventh day, or Saturday, just as God created the world in six days and then stopped. They leave nature alone for the day.
Even starting a fire is banned, so many Jews, mostly Orthodox, don't drive – since that involves combustion – and live within walking distance of their synagogue. In the same spirit, Yahweh told the Israelites to leave fallow their farm fields during the sabbatical year, an ancient form of rejuvenating soil.
The early Christians switched their attention to Sunday, when Jesus rose from the dead. Like the Jews, some Christians consider the day itself to be holy and, traditionally, avoid anything that detracts from its divine nature: work, business, and shopping. Though their primary obligation is to attend services, they also imported the Sabbath spirit of rest and joy.
For Muslims, Friday is holy. They don't sanctify this "day of assembly," or Juma, with rest since God does not need rest. In the Koran, Allah directs Muslims to attend congregational prayers at midday but they can then return to work. But Friday is a day off in many Islamic countries, and Muslims consider Juma a time for charity, family, and quiet enjoyment.
Each religion's teaching makes a powerful case for calling it quits one day a week. Many nonreligious people take a weekly rest as well. If we all reduced our driving, shopping, business, and energy consumption by one-seventh, we'd pollute that much less. We'd have to avoid energy-guzzling leisure activities, so maybe nix the long drives or movie marathons. Still, even if we left out the work and traffic that must go on – hospitals, police, utilities – the environmental boon would still be significant.
Religious leaders have joined to battle global warming and preserve God's creation. But in their rush to recycle, reduce, and reuse, they have neglected the pollution-reducing potential of a full-day work stoppage.
The Evangelical Climate Initiative, launched last year by 86 leaders, calls for international action but also directs concerned Christians to "keep your tires properly inflated" and "walk or bike more." Why not invoke the Sabbath and suggest that people live near their church and keep Sunday holy by not shopping or working? Then they could skip all driving one day a week.
In a national campaign, hundreds of Jewish synagogues are installing compact fluorescent light bulbs. A good start, but by traditional rules, Jews would not turn on any electrical appliance on Shabbat, a much greater savings.
In its "Shrinking the Footprint" campaign, the Church of England also singled out bulb-replacement, as well as switching off parish photocopiers at night. How little to ask, compared with the Sundays of 100 years ago when all commerce halted on wharf and factory alike.
Global warming has united the monotheistic faiths despite their other frictions. In the past week, Jewish, Christian, Muslim, and other religious leaders from around the world have convened yet again for a symposium on the environment, this time in Greenland in part to focus on a melting glacier there.
Together they could do much more by hewing to one of the oldest practices in their common tradition.
• Christopher D. Ringwald is the author of "A Day Apart: How Jews, Christians, and Muslims Find Faith, Freedom, and Joy on the Sabbath."