suspect that people are more likely to be insulted by the former than the latter.

Strange, but probably true!

And yes, it's the soundbitiness I find annoying, rather than the expression of atheist sentiment. I tend to cringe when I see Alpha Course ads (although at least they generally play up the 'asking questions' aspect). But the hell-fire sort of thing makes me mutter 'get off my side, damnit' (although I'm not sure that they would see me as being in their club, anyway!).