The Catholic philosopher (and former atheist) Edward Feser has a great post up discerning among types of atheism, and why the most popular form of atheism today is the worst, most irrational sort. Excerpts:

Consider first the different attitudes an atheist might take to the theoretical side of a religion.  There are at least three such attitudes, which, going from the most hostile to the least hostile, could be summarized as follows:

1. Religious belief has no serious intellectual content at all.  It is and always has been little more than superstition, the arguments offered in its defense have always been feeble rationalizations, and its claims are easily refuted.

2. Religious belief does have serious intellectual content, has been developed in interesting and sophisticated ways by philosophers and theologians, and was defensible given the scientific and philosophical knowledge available to previous generations.  But advances in science and philosophy have now more or less decisively refuted it.  Though we can respect the intelligence of an Aquinas or a Maimonides, we can no longer take their views seriously as live options.

3. Religious belief is still intellectually defensible today, but not as defensible as atheism.  An intelligent and well-informed person could be persuaded by the arguments presented by the most sophisticated contemporary proponents of a religion, but the arguments of atheists are at the end of the day more plausible.

Feser says that there are three similar degrees of hostility an atheist can have towards the “practical” side of a religion — that is, its moral teachings, its rituals, and so forth. He calls these A, B, and C. So an “A1” atheist would have the most contempt for religion, while a C3 atheist would have the most respect for religion, though ultimately would remain an atheist. Feser continues:

I find that atheists who fall on the most negative ends of these scales — A1 territory — are invariably the ones who are the least well-informed about what the religions they criticize actually believe, and the least rational when one tries to discuss the subject with them. And when you think about it, even before one gets into the specifics it is pretty clear that A1 is prima facie simply not a very reasonable attitude to take about at least the great world religions. …

When one considers the prima facie implausibility of the A1 attitude together with the ill-informed smugness and irrationality of those who approximate it, it is pretty clear that its roots are not intellectual but emotional — that it affords those beholden to it a sense of superiority over others, an enemy on which to direct their hatreds and resentments, a way to rationalize their rejection of certain moral restraints they dislike, and so forth.  In other words, A1 atheism is pretty much exactly the sort of ill-informed bigotry and wish-fulfillment A1 atheists like to attribute to religious believers.

And here’s the thing: If there is anything new about the New Atheism, it is the greater prominence of atheists who at least approximate the A1 stripe.

Lord Martin Rees, probably the most important British scientist alive today, strikes me as a C3 atheist — the kind who finds religion implausible, but who respects religious believers and finds that religion serves many positive ends. That is why so many prominent atheists spited him for his Templeton Prize: because he’s a walking, talking refutation of the idea that intelligent atheists are obliged to hate religion and religious believers, and condemn them across the board as dangerous fools.