Before you dismiss the question out of hand, consider these four inter-related bits of evidence:
1) As recently reported in the New York Times, military personnel who identify themselves as "Atheists" have requested chaplains to tend to their spiritual needs. As the Times article notes, "Defense Department statistics show that about 9,400 of the nation's 1.4 million active-duty military personnel identify themselves as atheists or agnostics, making them a larger subpopulation than Jews, Muslims, Hindus or Buddhists in the military." Having their own chaplains, the article explains, would give Atheists a sense of legitimacy and help validate their own system of values and beliefs.
2) The U.S. Government reports that in 2008 those identifying themselves specifically as "Atheist" composed the 18th largest group of 43 possible categories of "self-described religious identification." The number of persons so identifying themselves almost doubled from seven years earlier. Admittedly, "Atheist" is one of the options listed under "no religion specified," but given that other options for respondents included checking "Agnostic" or "No Religion" or not answering the question at all, it appears that identifying oneself specifically as an Atheist, as opposed to simply "not religious," is growing in appeal. This points to the utility of a distinction made by Jonathan Lanman between "non-theists," those with no particular religious belief, and "strong atheists," those who view religion not only as irrelevant but as misguided and dangerous.
3) Similarly, it's worth noting the degree to which Atheists routinely, strategically, and often vociferously position what is often described as their "secular-humanist" views against religious traditions. Read or listen to any of the celebrity Atheists of the past decade like Richard Dawkins, Christopher Hitchens, and Sam Harris and you realize that they fashion many of their arguments not against some alternative economic, political, or philosophical position but against organized religion. Religious faith is clearly their primary opponent in the contest for the intellectual allegiance of the population, which makes it hard not to conclude that they offer their views and beliefs as a viable alternative to traditional religious systems.
4) Finally -- and you probably knew this was coming -- consider all the comments made by self-identified Atheists on articles published in the Religion section of the Huffington Post. Seriously. Either Atheists have way more time on their hands than the rest of the population or they've got something to prove. This assertive, us-against-them tone (in this case, against established religion) is characteristic of new religions. (Think of the Christian gospels', especially Matthew and John, stance toward first-century Judaism, for example.) As Rabbi David Wolpe observed a few months ago, there is an astonishing garrulousness to the comments made by Atheists to posts about religion that suggest not simply a lack of interest in, or even disdain for, religion but a competitive anger directed against persons of traditional religious faith. (Obviously plenty of religious folk radiate the same garrulousness, but this post is about Atheists.)
Taken together, these four elements suggest that Atheists regularly demonstrate attributes -- desire for spiritual sustenance, the importance of self-identification, offering their worldview as an alternative to other religious systems, and an assertive if not competitive style of engagement with other religious points of view -- usually exhibited by religious folk of all persuasions.
While Atheism as a movement doesn't have the formal structure, celebrations, or creedal dogmas of organized religions, we might at least identify Atheism as it exists today as an increasingly vibrant faith tradition. Still, when speaking of Atheists, why use the f-word (for "faith," silly) rather than speak of a worldview or personal philosophy? Three reasons suggest themselves.
1) It conveys that both a conventional religious worldview and atheistic worldview require a measure of faith. I don't mean this simply about the rather limited question of whether God exists, but rather about whether the material, physical dimension of life immediately apparent to our senses is all there is. The question can't be reduced, as Atheists regularly have, to observing that there are many beliefs -- in the Tooth Fairy and Santa Claus as well as God -- that can't be proved and must be taken on faith, but rather to ask whether there is a dimension of existence that supersedes or eludes our physical senses. Ultimately, any speech about God implies such a dimension that conversation about the Tooth Fairy and Santa Claus do not.
2) Religious faith -- and I'd argue atheistic faith -- doesn't begin and end with the question of God or a spiritual dimension to life. One needs also to construct an interpretation of life (describing its purpose, goal, worth) and set of values by which to live that life. Ethics and values are not self-evident from religious creeds -- witness, for instance, the distinct values of the varieties of Christianity, Judaism, and Islam that run the gamut from liberal to fundamentalist. Similarly, there is no self-evident value system shared by Atheists and projecting such a system requires imagination, critical reflection and, yes, faith.
Third, characterizing both organized religion and emergent Atheism as distinct faith traditions invites a measure of mutual regard and even respect that is sorely lacking in present discourse. Professing belief in God, as well as rejecting such belief, each requires equal measures of imagination and nerve. As it turns out, doubt is not the opposite of faith; certainty is. For this reason, we can hold out the hope that religious and non-religious believers alike may recognize in each other similar acts of courage and together reject the cowardice of fundamentalism, whether religious or secular. Being able to disagree respectfully is a small but significant step that believers and non-believers could take as they, together, contemplate admiring, understanding, and preserving this wondrous world we share.