This article puts its finger on one of the problems I’ve long had with the so-called new atheism:
[I]n its basic outlines [A.C.] Grayling’s humanism is that of the nineteenth-century positivists, who built a philosophy around their belief in the perfectability of human nature. For Grayling, and for the other New Atheists, reason doesn’t just answer questions about our origins and our ethics; it moves us toward that city on a hill where, [Grayling’s] The Good Book promises, “the best future might inhabit, and the true promise of humanity be realized at last.”
Meanwhile, this article published in the Nation a few months ago makes a similar point, and also notes how positivism can be yoked to a reactionary political agenda (such as Christopher Hitchens’ and Sam Harris’s embrace of the “war on terror” as an Enlightenment crusade against religion).
What’s striking about all this is that you still have, in the 21st century, people claiming with a straight face that science and reason are the royal roads to absolute truth and moral and political progress. At one time it had become something of a truism that the 20th century, with its world wars, revolutions, and genocide, had put paid to 19th-century optimism on behalf of capital-R Reason and capital-P Progress. And the gas chambers and the atomic bomb were thought to have demonstrated pretty definitively that scientific, technocratic reason could be neatly yoked to the most abominable moral and political goals imaginable.
Both religious and atheistic thought responded to this sense of disillusionment. Christian theology rediscovered its doctrines of human brokenness and original sin; atheism, in the form of existentialism and Freudianism, honed in on the irrational impulses and drives that actually govern much of our lives. Neither was much inclined any longer to speak blithely about the omni-competence of reason or the inevitability of progress. Moreover, both were willing to attend to sources of insight that fell outside of the scientific, narrowly construed. 20th century thought, across a wide swath of disciplines, came to see reason, understood solely as discursive or deductive thought, and empiricism, understood in the manner of logical positivists and their verifiability criterion, as only a part of how we experience and make sense of the world. By contrast, the neo-positivism of the new atheists looks downright old-fashioned.
I certainly don’t think Christians should despise the Enlightenment, as has now become fashionable in some theological circles. At the same time, the version of the Enlightenment embodied by positivism invariably ends in reductionism and scientism. This in turn produces a very narrow understanding of what “reason” is and a correspondingly constricted view of truth, morality, and human experience generally. Religion and humanism alike should oppose it.
A Thinking Reed 
I think you are right about the positivism of the gnus.
They are solid materialists – or “physicalists,” if you prefer – as well, unlike the Logical Positivists of the early 20th Century.
Their optimism about reason is as silly as you say and makes no sense at all in people who can’t but believe that “reason is the slave of the passions” – or of the instincts, as they might prefer to put it.
And sometimes the “we will do away with all that” attitude, at least of Dawkins with regard to religion, reminds me of 19th Century Russian Nihilism.
Neither Harris nor Hitchens seem quite as radical.
Like post-Holocaust “death of God” theology, their outlook seems dominated by a single historical phenomenon, in their case the post-Cold War rise of deeply reactionary Muslim terrorism and especially 9/11 and its aftermath.
And that has made them cheerleaders for the whole absurd and continuing episode of the neocon wars.
I continue to agree with the Enlightenment and its 19th and 20th Century successors in esteeming scientific and technical progress along with the increases in health, wealth, and well-being they enable good things.
I think much the same of the progress of the world from despotism and slavery to the much less harsh regime of bourgeois democracy and wage-slavery.
And while one has to hope improvements of those kinds can continue even in the face of finite resources, excessive population growth, and degradation of the natural environment by us humans and our activities there does not seem any special reason to suppose they must, or that they will or even could be accompanied by decline of the horrific aspects of human history.
The global progress of neoliberalism and its depredations, of course, don’t bode well for the immediate future.
Recent developments in DC, in particular, bode ill especially for America.
Pingback: New atheism as 19th-century positivism redux | A Thinking Reed « Atheism « Theology of Ministry