But it is one thing to disbelieve in God; it is quite another to never feel a twinge of doubt about one's own disbelief. And just as the Christian who has never entertained doubts about his faith probably hasn't thought hard enough about the matter, the atheist who perceives the Christian God and the flying spaghetti monster as equally ridiculous hypotheses really needs to get out more often.
This is an often-hurled criticism of atheists that really isn't true. From both my own 'journey' and from actually reading Dawkins, Harris, et al. (i.e. reading the book cover to cover, not just selecting certain passages, a habit I suspect of most atheist-critics), I can say with confidence that atheists aren't lacking in the doubt department. Indeed, since most atheists are born into at least nominally-religious families, and grow up in a pretty religious society, it is hard to accuse atheists of having too little doubt, since it is precisely the high levels of doubt that brought them to where they are.
At some point (usually the span of several years' worth of reflecting, not some Aha! moment) some folks determine that atheism is the correct prism through which to view the world -- not the most convenient, not the most popular, but the most factually accurate. These atheists get to this point from some combination of:
1) Studying science -- it is hard to find an atheist who isn't pretty familiar with either astronomy (the vastness of the universe in which we live) or evolution (the simplicity of a process that produces complexity with no intelligent designer).
2) Historical awareness -- the realization that most religious traditions are from a time when demonic possession was a recognized medical ailment, more than half the earth hadn't been discovered yet, and people tended to live to the ripe old age of 42. Additionally, newer religious traditions such as Mormonism, Scientology, etc. are just insane, and seem more insane simply because they are newer, not because they are any more or less tied to reality than the older ones.
3) Corruptness of religous institutions -- this may apply to Catholics only, but after being told over and over that the pope is infallable, and then learning the history of the Catholic church (e.g. Holocaust, blind eye towards) and its current teachings (e.g. women, inequality of; homosexuals, evilness of) and practices (e.g. little boys, touching of), well, some cracks start to emerge in the dam.
I'm sure there are other common factors, but this covers a good chunk. So instead of arguing that atheists lack doubt, which, again, is hard to square with how they became atheists, I would instead suggest that atheists have very open minds to the concept of a god, but have failed to encounter any evidence that would overturn their worldview. One possibility is that atheists are open-minded and doubt-filled people who discover atheism and then close off their mind and never "lose faith" in their atheism. The other possibility is that some people -- who, via genetics, upbringing, whatever, are open-minded and doubt-filled -- tend to find atheism and remain open-minded and doubt-filled. To me, the latter seems much more in keeping with my own experience and the general idea that people don't change very much.
Tangentially, I was happy to hear Obama mention non-believers in his Inaugural Address, and I'm further encouraged that he continues to use that phrase, as he did when being interviewed on Arab television the other day, in describing the mish-mash of religious beliefs in America.