Religious fervour, perhaps, or holding the place that religion holds for some, giving meaning, direction, and purpose. Not worship. It's not as much a first-cause thing, more of final destination thing.
No different than any kind of "-ism". Capitalism, Communism, Socialism, Fascism, Liberalism, Conservatism...different blinders looking at the same pile of crap. Any can be followed with religious zeal.
I suspect that tendmote isn't so much slippery as much as he isn't clarifying arguments to your level of satisfaction before posting, or is just posting ideas for discussion, and therefore is not posting his beliefs, which may come up later. Not everyone who posts is looking for an carefully posted logical argument, just a fun discussion.