Religion and sustainability

Sustainability is an interesting issue. I have a friend, a hippy but for wanting for a better term, and she has a “bumper” sticker on her bag reading: “The earth does not belong to us, we belong to the earth.” She then believes that we do have a responsibility to future generations. Her argument comes from her basic belief system. She beliefs that each person is an extension of the gaya and in death we realize the connection. She then uses this as a statement that any damage done to life and the earth is damage upon yourself as a whole. We discussed in class about religion being the driving force for the idea of sustainability and the responsibility for future generations.
But a question still keeps asserting its self; what is harm? Surely natural activities of animals isn’t harm. If a loin kills to eat he is sustaining himself, his offspring and his species. So, using the fruits of the environment isn’t harm. What then is?
Her response was any action which eliminates other species or human life in the long run. She was then worried about global warming, mostly caused by carbon emissions. She also worries about the destruction of the rain forest and related issues. I then asked her another question, what does sustainability mean to you? Her response was interesting. She said the most important issue was to respect nature and use just the bare minimum of resources to survive. She also believed in local made products and natural methods of production.
Also during class with discussed that these methods bring about poverty. But her response was what one would typically expound. It was only lower material consumption, but not wealth in other senses. Her argument was that by our vast material wealth has detracted from human interaction and therefore we are worse off then if we didn’t have as much material wealth. This is an interesting idea with one possible hitch, what about personal preferences and liberty? Her argument was that we would realize only once we eliminate excess material possession.
Her arguments seem to ring in the same tone as our current book: For the Common Good. I think this shows how one then argues for sustainability, through some sense of a higher power. I don’t see another way in which to argue for sustainability and then government interference to achieve sustainability.