Plentiful energy for economic production is the basis of the industrial world's material comfort; but the present pattern of fossil fuel consumption can not be sustained even for a few decades longer without major future global environmental impact and probably disaster. Thus energy is perhaps the archetypal challenge to sustainability. Technical solutions to energy needs are vital. Renewables and fission can play important roles. Harnessing thermonuclear fusion, the energy source of the stars, has long been an ideal. It has motivated much of the past half century of plasma physics. Fusion is now at a cross-roads. Plasma science has developed magnetic confinement configurations that appear adequate for producing sustained fusion burn, but a demonstration experiment will be big and expensive, with the economic benefits seeming distant. Every technical solution is double-edged. There is no purely technological fix for energy needs or for most other environmental concerns. Changes in habits of consumption, expectations, population, and values will become essential in a sustainable-energy society. These are ultimately spiritual values. Religious faith is the primary source and sustainer of such values, and provides major teaching resources for guiding individuals and society. It is not sufficient, though, to attempt to manipulate those resources in support of secular objectives, however worthy. Religious teaching has authority only when true to God's call. Society cannot at the same time discount religious values in economic or cultural matters and hope to recruit their help in challenges of sustainability.