The faith of a green anarchist is faith that the sun will rise tomorrow. As the winter solstice is the longest night of the year—the light’s longest absence—it could be understood as one of our High Holy days when this faith is most severely tested and hope may be restored. It is, and must be, an article of faith that the sun will once again rise and that the light will return to nourish us; that, as John Muir wrote, “this is still the morning of creation”.
Many will object and insist that we know the sun will rise and that therefore no faith is required. But that claim relies on the validity of what is likely a false binary between faith and knowledge. It is also a claim to know the future. It is human arrogance. That the sun has, in fact, risen quite consistently in the past provides merely the grounds for confidence, not certainty. It suggests merely that our faith is not of the blind variety.
To push the point a bit further, one might stack up a mountain of books, assemble a stadium of experts, and compile all that we seem to know about gravity, planetary motion, the life cycle of a star, and the rotation of the earth but he or she will nonetheless fall short of certainty. There will remain a gap that knowledge cannot bridge; to get to the other side one can only leap.
The unstated assumption originally pointed out by David Hume is that the law-like regularity of past events will continue uninterrupted into the future. There is no—non-question begging—evidence available to justify that assumption. We do not and cannot know that the future will resemble the past in the ways that would be relevant to this inquiry.
Green anarchist faith may therefore be grounded not in what we know but in an awareness of and sensitivity to our animal limitations; limitations that are not temporary obstacles that we might one day overcome but that are inherent to being corporeal beings. The human mind has access to some aspects of reality but by no means to the whole of reality. David Abram explains:
“Each creature—two-leggeds included—has only a restricted access to the mystery of the real. As a human I may have compiled a great mass of data about the ways of the world, yet in a practical, visceral sense…an earthworm knows far more about the life of the soil than I do, as a swallow knows far more about the wind. To be human is to have very limited access to what is.” [emphasis added] 
Furthermore, human language does not and cannot perfectly map or mirror the world. All language use is necessarily imperfect, incomplete, and distorted. With every move, language leaks truth like a worn out bucket and introduces error. The impact of this on our overall knowledge of the world is vast given how much of our beliefs are filtered through language and dependent on the testimony of others.
So our projections and forecasts are always uncertain. To suggest otherwise is to reduce reality to a simple machine—perhaps civilization’s favorite metaphor—where each event follows the next as a matter of course, where the ending is predetermined and wholly predictable, where we have access to the whole of its operations. But if reality must be likened to a machine it is of the black box variety where we have nothing but observed inputs and outputs and very little beyond speculation as to its internal churning. We may at times be able to predict the output but, in ways both better and worse, are regularly mistaken and surprised.
Given the number of doomsday scenarios and apocalyptic visions currently in circulation, the fact that we are often mistaken should be understood as a source of hope and encouragement. There are more variables at play than we can possibly be aware of and so our nightmare visions may not come to pass. To give up hope and abandon resistance is to treat humanity as an all-knowing deity rather than as an animal operating with limited knowledge and finite senses.
During this time of year, every day is shorter than the last; darkness claims an ever increasing portion of our existence. The trajectory can be discouraging; we may come to feel estranged from the sun. The winter solstice is the point when that changes; when darkness yields to light and the days gradually grow longer. In this way it is holy.
I have faith that the sun will return and we will again be well.
 Abram, David. 2010. Becoming Animal: An Earthly Cosmology. New York: Vintage, p. 217