The first sort of atheist has a perspective which I would see as descending from Hume via the Logical Positivists (although it has much deeper roots - see this book), and this tends to be the dominant form of atheist expression on the web, at least as I have experienced it. A classic expression of the attitude might be Hume's declaration about books:
When we run over libraries, persuaded of these principles, what havoc must we make? If we take in our hand any volume; of divinity or school metaphysics, for instance; let us ask, Does it contain any abstract reasoning concerning quantity or number? No. Does it contain any experimental reasoning concerning matter of fact and existence? No. Commit it then to the flames: for it can contain nothing but sophistry and illusion.
Hume, Enquiry Concerning Human Understanding, XII, iii
This sort of atheism sees no value whatsoever in any religious perspective, considering it 'illusion' at best - and a prop for the psychologically inadequate, evidence of neurosis, and fuel for sociopathic behaviour at worst. This is the sort of atheism that I see as aspect blind, in that there is an entire way of seeing the world which is cast away when religious perspectives are cast away. I see this form of atheism as, at best, ignorant of philosophical history (let alone theology) and intellectually crippled at worst. The crippling lies precisely in the way that the wisdom traditions of the different religious traditions in the world become opaque to this perspective, they are simply more or less variable manifestations of the human capacity for self-delusion. This crippling I call asophic, and it ties in with a particular attitude which tends to exalt science as being hard-headed and reasonable, a fit pursuit for strong and manly men; whereas religious flummery is suitable only for weak-willed women who crave emotional gruel to get them through their days. There is a clear historical genealogy for this perspective but, as I've said before, philosophically speaking this position is not just inadequate it is manifestly inadequate. I don't believe that anyone who enquires into the matter, who is equipped with a modicum of good sense, compassion and open-mindedness, could now be persuaded of the rightness of this view.
So why am I calling it 'humourless'? Simply because it seems analogous to having a sense of humour. You either get the joke or you don't. You either get the sense of what a wisdom tradition can provide, or you think it's all meaningless gibberish. The image that best encapsulates the poverty of this perspective is, for me, a story about Wittgenstein (regular readers will not be surprised). In the 1920's Wittgenstein visited the Vienna Circle, who revered Wittgenstein's Tractatus as the apotheosis of the Humean perspective. Wittgenstein realised that the Circle had completely failed to 'get' what he was driving at (Wittgenstein being very much someone who had a 'religious point of view') and so he turned his chair around and began reciting the poetry of Rabindranath Tagore to them.
Now I would really want to emphasise that this form of atheism, whilst common, is not at all the only form of atheism that is intellectually possible and so I want to describe a sophisticated form of atheism, and I'm calling it sophisticated simply because it is distinctly not guilty of adopting an asophic perspective: it is conversant with different wisdom traditions and what they mean, it is clear-sighted about the western intellectual tradition, and, most especially, it doesn't buy into the mythology of science.
This sophisticated atheism can be distinguished from the humourless sort most clearly by a) a recognition of the need for a wisdom tradition in human life, and (most pertinently from my point of view) b) a willingness to consider seriously the teachings of the different wisdom traditions that exist in the world. They don't, therefore, see wisdom traditions as by definition meaningless. Examples of this sort of atheist might be Terry Eagleton or Martha Nussbaum (and, possibly or probably, Wittgenstein himself).
Such a person may, for example, ponder the Christian tradition deeply, ponder the problem of evil even more deeply, and come to the considered view that the Christian intellectual tradition is inadequate to serve as a guide within this world. Or they might ponder the historical narratives of the gospels, become persuaded that the resurrection simply didn't happen in any way related to what is described, and find that they simply cannot believe Christianity. They might therefore adopt one of various non-Christian perspectives, Buddhism perhaps (which is effectively Robert Pirsig's stance), or - in Nussbaum's case - a form of Stoicism. Such perspectives are demonstrably atheist, but they are also intellectually sophisticated and humanly rich; they aren't simply abstract philosophical structures but parameters within which a meaningful life can be pursued.
Humourless atheism is essentially a parasitic exercise: it tends to focus on criticisms of a religious tradition (normally North American fundamentalist Christianity - what I call Modern Protestantism) rather than advancing any positive project of its own; it tends to rely on an inherited epistemology that places scientifically established truth at the top of the hierarchy of knowledge; and it displays no grasp of any theological tradition (whether that be Christian, Buddhist or any other). There are various arguments that get used repetitiously and, more often than not, a failure to actually listen to what is being claimed from a religious perspective. In particular I have often found that when I describe a theological perspective that doesn't fit with what is being criticised I am described as being 'modern' or 'liberal' which a) isn't true as my position is basically orthodox (and rooted in first-millenium faith) and b) serves only to reassure the humourless atheist in their prejudice that Christianity is intellectually defunct, and so cannot evolve in any way.
So, to sum up: humourless atheism is intellectually weak and humanly myopic; sophisticated atheism is well-informed, self-aware and rich with insight and possibility. Whenever I go on a rant about atheism - which I expect to do on a regular basis in this series - it will always be the former that I have in mind. When I discuss the more sophisticated atheisms I will tend to describe them in a more positive way (in both senses) eg as stoicism, buddhism, humanism etc.
I intend to explore various things in this sequence of posts, including some standard responses to the common arguments that humourless atheists make; I'll go into some depth as to what a wisdom tradition is and why they are essential; and at the end I'll say something about why, for me, Christianity is not just intellectually reasonable but much more reasonable than humourless atheism. That's the plan for now anyhow!