I think some of the invective develops out of a confusion over the difference between religion and "religion." Emery is concerned to talk about the former, in the terms of how we might define it, by just looking at the content of various religions and trying to come up with its minimal content. TenaciousMcD, in the comments, offers a political response, that I think is focused on the latter: the discursive and therefore political use of the term, what it means in context. The evidence for my hypothesis can be found within the flame war between TMcD and CuratLex, where the latter does in fact assume that the former is not religious precisely because TMcD supports the democrats.
I'm thereby reframing TMcD's original argument, but basically I buy what he says:
what exactly are the minimal requirements to qualify as "religious" in today's non-creedal America? I think there are really two: 1)you profess to believe in God; and 2)you at least lean Republican on cultural issues (abortion, gay rights, etc.). The sign of being VERY religious is that you strongly support the GOP on BOTH cultural and economic issues.
Now this may not make much logical sense since the major criterion (the second) is not religious at all. But what I would suggest is that, precisely due to the lack of natural common ground among believers of disparate faiths, politics has filled the gap, and the GOP has rushed to offer a unifying political content to vouch for "religious" credibility.
My sense of things after a few months in the UK, is that this political construction of "religion" ("filling the gap") has not occurred here, and for that reason religion doesn't matter much at all (which is not to say there are no believers here). This creates a context in which it would be easier to have the discussion that Emery initially aimed to have. I think that in the US it's almost impossible to talk about religion without invoking the politics that TMcD describes, and that's because of the success of the radical right's effort to tie religious symbols to political affiliation, and vice versa.
I wonder if it doesn't also have something to do with faith. I don't know many folks who have genuine faith, but the one's that do (one sometimes reads this blog, and one is TMcD himself) don't seem to have any interest whatsoever in politicizing that faith. When those on the right in US politics politicize theirs, I tend to assume, then, that they don't really have much faith at all.