there is an alternative to thanking God on the one hand and seeing the universe as a “cosmic lottery” or as absurd on the other. An alternative to being grateful to a deity or to ignoring such feelings altogether. Think of the sun's warmth. After all, the sun is one of those forces that make possible the natural world, plant life, indeed our very existence. It may not mean anything to us personally, but the warmth on our face means, tells us, and gives us a great deal. All of life on Earth has evolved in relation to this source of heat and light, we human beings included. We are because of, and in our own millennial adaptation to, the sun and other fundamental forces. My moment of gratitude was far more than a moment's pleasure. It is a way of acknowledging one of our most intimate if impersonal relationships, with the cosmic and natural forces that make us possible.
I wouldn't deny that it's possible for non-theists to have genuine feelings of gratitude even beyond the sorts of transactional gratitude everyone experiences every day ("thanks for the coke, here's a dollar..."), but I'm not sure Aronson really shows that non-theistic (or maybe non-purposive) views of the world really get you to defensible claims for gratitude, rather than just a "feeling." After all, when Aronson talks about "impersonal relationships" it's not really a relationship, it's a much more generic connection. The sun would - on his terms - burn just as brightly if we weren't here. We don't have a relationship with the sun, any more than the millions of people who buy tabloids have a relationship with the celebrities they think they know.
Indeed, on Aronson's take, it's hard to figure out how we might have gratitude for the most distinctive thing about us, that we are able to think about whether to actually be grateful or not. Our rationality, our consciousness, our ability to philosophize, so to speak, really sets us off from the rest of nature (so far as we know). In what sense can we be grateful for that thing that goes a long way toward making us "us" if the "us" there is just the product of blind, impersonal, non-purposive processes? Not much, it seems to me.