New Atheism currently refers most often to atheists who confront and challenge religious arguments and religious practices. This can be done in print through published works, online through digital publications and social media, and in person often through atheist organizations and meetings. A defining characteristic of New Atheists is that they believe mainstream religions like Christianity make no more sense and have no more validity than the typical mythology does.
The term began getting attention in the early '00s as a pejorative label used by theists and agnostics for outspoken atheists. Critics assumed new atheism was a sort of fad or that it was arrived at through ill-reasoned, irrational, or unsound means.
Though atheists considered new atheists at first relisted the term, it eventually some of those atheists grudgingly accepted the term as a convenient label for atheists such as themselves who take part in openly refuting, mocking, and answering contemporary challenges to humane treatment of people presented by religions and to threats to justice, equality, democracy, free speech, and secularism in the world as posed by theism. So it is that the term New Atheists generally encompasses atheists who have a gauche predilection for stating in public that they are, in fact, atheists, and worse, arguing publicly for their point of view, and worse still, drawing large audiences in doing so whether that be on a website, a blog, a podcast or through a book, news media appearances, or video productions. The term New Atheist is somewhat unevenly embraced by those so described.
History of the Term
The traditionally pointed to origin of this label for atheists is an October 22, 2006 article in Wired magazine by Gary Wolf currently titled "The Church of the Non-Believers" (originally titled "Battle of the New Atheism" according to the Richard Dawkins website, and likewise discussed under that title on Pharyngula) that explicitly mentions Richard Dawkins, Sam Harris, and Daniel Dennett as the prototypical New Atheists. However, the exact origins of the label itself are murky as are the connections between people using the term pejoratively. Indeed, the labelling of prominent contemporary atheists as new appears to be a perennial theme amongst atheism's critics, pushing one atheist, Luke Muehlhauser of Common Sense Atheism to go so far as to label this the second New Atheism as opposed to the first New Atheism of the '70s and '80s. In fact, other incidents where a person used the term New Atheism or New Atheist that predate Gary Wolf's Wired article are:
- 1966: David Haxton Carswell Read published Whose God is Dead: The Challenge of the New Atheism which, according to blogger Arizona Atheist, cries foul at the atheists of the '60s who want to build up the wall of separation between church and state and create a more secular society, and then claims atheists and theists are at a draw since neither can conclusively prove that there is or isn't a god.
- 1981: Michael Azkoul publishes Anti-Christianity: the New Atheism which, according to reviewer zonaras at Amazon.com, opposes "19th century... atheistic humanism" from an Eastern Orthodox Christian perspective.
- 1986: Robert Morey publishes The New Atheism and the Erosion of Freedom for the first time in which he launches a screed against the outspoken atheists of the '60s, '70s, and '80s (and later in various revisions) all of which reflect the same old arguments trotted out against atheists today.
- 2001: Richard Weinstein publishes New Atheist Majick, a little heard of philosophy book that seems to be a self help course on atheist metaphysics.
- April 18, 2006: Catholic Bishop Edward K. Braxton gives a keynote speech at the National Catholic Educational Association's 103rd Annual Convention titled, "Charting a Course for the Future: The Need for a New Apologetic", in which he laments "The New Atheism" and the ease at which children on the Internet can run across the writings of Daniel Dennett, Sam Harris, and the like along with other writings critical of Christianity that, in turn, religious apologists will be hard pressed and even unable to counter when asked about by an inquisitive child. Braxton's speech was noted at Pharyngula on April 20, 2006 by wamba.
A Misapplication of the Word "New"
From the very beginning when people began labelling outspoken atheists as New Atheists, atheists themselves were quick to point out that there is nothing especially new about New Atheists. Indeed, there seem to have been New Atheists at all times, even before Christianity and most other ancient religions existed, possibly beginning with the Cārvāka atheists of India in the 6th century BCE and ancient Greek philosophers such as Diagoras and Theodorus.
And going back just a few decades into the 20th century in the United States, one finds a wide spectrum of outspoken atheists such as Madalyn Murray O'Hair, Ayn Rand, and James Randi, none of whom shied away from the media spotlight. If it weren't so convenient to have a label for atheists who care about their atheism and unabashedly speak out against religion and theism, the application of the word new toward such atheists would be seen as just another data point in the way theistic thinking has failed for as long as it has been known to exist.
The Scarlet Letter
One of the most successful aspects of New Atheism has been its ability to turn criticism into opportunities to spread public awareness about atheism by harnessing a wide variety of creative talents. One such opportunity arose following an attack on New Atheists in the Washington Post by Matthew Nisbet and Chris Mooney. In response to this attack, PZ Myers used his characteristic verbal acuity to refute Nisbet and Mooney's nonsense in April of 2007 on Pharyngula, and ended up writing this brilliant metaphorical description of what New Atheists do:
And it certainly is true that Dawkins puts an exclamation point on godlessness, and good for him. The path we've taken in the past, the cautious avoidance of the scarlet letter of atheism, has not worked. Dawkins represents a different, bolder, more forthright approach — we are staking out a place in the public discourse and openly discussing our concerns, rather than hiding in fear of that old Puritan scowl. We will not go back in the closet. [Emphasis added.]
Richard Dawkins at the time had been operating his own organization, part of which included the Out Campaign which advocates for atheists to come out of the closet as atheists to people around them, much like LGBT people have prompted each other to come out about their gender identity and/or sexual orientation to great political and cultural success. Dawkins' main person in charge of his foundation in the USA at the time also happened to be Josh Timonen, and when Timonen read the part in PZ's writing about the scarlet letter of atheism, he had a stroke of genius and put the scarlet letter quite literally on a t-shirt, a design that Dawkins referred to as "stunning" in revealed correspondence with Timonen.
Now, PZ had already asked his readers to think up "a logo for the godless" , as he put it, in October of 2006. His ideal logo requirements proved to be difficult to meet, however, just as PZ had imagined they would:
The kind of thing I would be looking for is something simple, fairly abstract, easy to render, and that wouldn't antagonize deists, agnostics, or atheists. It should be positive: no crucifixes with a slash through them, for instance. It shouldn't be weird—no flying spaghetti monsters, please—it shouldn't be ugly , it shouldn't be in-your-face and gloating, it should be unobtrusive. It ought to be the kind of symbol that if it were done up as a piece of jewelry, it would be tasteful.
The scarlet letter turned out to fit those requirements so beautifully that PZ shared the scarlet letter of atheism t-shirts on Pharyngula the very same day that Timonen thought up the design. It has become one of the most visible and vivid symbols of New Atheism to this day, featured today on numerous atheist blogs and websites as well as the t-shirts where it began.
The New Atheist "Threat"
One common theme in the pushback against efforts by atheists to organize and build both physical and online communities is that atheism is seen as a dire threat by the religious to their way of life even though atheism at its most basic amounts to teaching the religious that they are wrong about reality and asking for or legally forcing them to stop treating other people as subhumans due to some religious dogma or hubris. The sense that religions are losing ground has indeed been supported by evidence in the United States, New Zealand, the United Kingdom, and elsewhere around the world. 
Despite that, religious believers, especially Christians in the USA, have managed to maintain their ability to be allowed to preach as they like and unfortunately continue to be allowed to partake in barbaric religious traditions including the brainwashing of young children into believing false things; the choosing of divine intervention over rational analysis and action; the virtual enslavement, disenfranchisement, and dehumanization of women; and the forced ritualistic mutilation of body parts on babies and children of all sexes who, given their age, are incapable of giving consent (consent that no reasonably informed and legally capable adult would give).
To the New Atheist, the facts are clear: the only threats are the ones imposed on us by religious beliefs and practices.
- New Atheism at the Atheism Wikia
- New Atheism at Wikipedia
- Why Atheism Will Replace Religion New Atheists and ordinary atheists are winning!
- Faith No More: Why People Reject Religion This book explains why people stop believing in Sky Daddy, also that atheists aren't the way believers stereotype us. Phil Zuckerman, the author at least once had dinner with PZ. 
- Two images of the militant atheist And they both feature creepy weird aliens! Entertaining cartoons.