A few days ago I saw some blog comment, I forget where it was, but it was something like, “It’s not atheism that I mind all that much, it’s just atheists’ incredible air of smugness about it.”
Being convinced about the high probability of something because your epistemology forces you to be given the observed evidence cannot be an act of smugness or unsmugness itself. I suppose it’s how you present it, but people trying to avoid debating the central core of any given argument will always accuse the other side of smugness, to change the subject.
Of course, the issue is really about status. Low or medium-status people are not allowed to make controversial assertions that contradict the cherished beliefs of high-status people because this is seen as a social power grab. Furthermore, there are many low-status people that indiscriminately oppose the cherished beliefs of high-status people for their own satisfaction.
For more on this, see “The 9/11 Meta-Truther Conspiracy Theory”.