First, let's define atheism as the rational position of disbelieving the existence of that special, human invented category termed the "supernatural". There is nothing new about atheism in so far as disavowal of the content of religious mythologies has a long history.
The "New" element to atheism refers to the recent vocalized communion of atheists who are calling for a replacement of magic-thinking and intolerance with rationality and mutually inclusive morality. PZ Myers does not like the term, New Atheist, yet he describes the position well, so here he is in response to Jonathan Haidt's misguided criticism of the New Atheism:
"The New Atheism isn't about throwing away moral systems or introducing a new dogma, it's about opening up a protected realm to inquiry and sweeping away old cobwebs, refusing to allow people to hide absurd ideas from criticism behind the foolish plea of faith. It's much more compatible with the spirit of science to question the follies of the priests than to argue that because priests hand out charity, we should overlook the fact that they also claim that gods speak to them and tell them who is naughty and who is nice, and that the good boys and girls will receive magical rewards."
"In light of this, it struck me then and still strikes me today that it is the height of
foolishness to think that Richard Dawkins is any significant part of the problem. Even more foolish is the idea that these sorts of religious beliefs are things to be pandered to, respected, and tiptoed around. Surely an essential part of any solution to the problem is loud and frequent public criticism of religious ideas that, let's be honest, can not be defended on any rational basis.
The only thing I don't understand is why that isn't obvious to everyone." ¬ Jason Rosenhouse on EvolutionBlog