In so far as that view is naturalistic, it could fall into the third or fourth options (metaphysical substance or physicality). In any case, the view I present in the second section is also supposed to be naturalistic, so it's a question of finding some aspect of nature that unites nonlife and life (roughly speaking). On my pantheistic view of nature, I think the answer is clearly the process of creativity.

You think religion produces rather than relieves us of alienation? It's surely meant to do the latter.

I don't see how you end up with a remedy at the end, when you've eliminated theistic religion (as we should), and we're left with the choice of how to respond to nature. The freedom to choose is the primacy source of angst, according to existential philosophers.