A key concept in economics is profit. Yet after at least a couple of centuries of intensive study, there is no generally accepted definition of profit, even among economist. We can't agree on defining it, but we can agree it's important. A key concept in human relationships in love. Most of us would probably agree that while love may be the most important single aspect of our lives, we are pretty much at a loss to define it.
Ecology assumes some natural order of things.
Regardless of whether our respect for nature arises from our belief in God or our belief in God arises from our respect for nature, ecology and spirituality are two dimensions of the same whole. The vast majority of us believe there is some higher unseen order of things, that there is a God, but we would be hard pressed to define it. I think most would agree that profits, love, and God are all important concepts, yet none of three has a generally accepted definition. And for most of us, the meanings are not so different as to create inevitable confusion or conflict. So let's find ways to work in harmony as we pursue the common purpose of building a more sustainable society.